Monoecious plants: description, representatives. Dioecious and monoecious plants Monoecious plants: characteristics
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Monoecious plants: characteristics
listen, let's study botany and chemistry together? bring a dioecious cucumber for a snack, and I’ll grab some undiluted alcohol!!
MONOOCYCY PLANTS, plants in which unisexual female (pistillate) and male (staminate) flowers are on the same individual, for example hazel, corn.
There are species in which bisexual and unisexual flowers can be found on the same plant. These are the so-called polygamous (polygamous) plants.
Walnut
After the pollen reaches the stigma in one way or another, its germination begins. The sticky and uneven surface of the stigma helps to retain pollen. In addition, the stigma secretes a special substance (enzyme) that acts on pollen, stimulating its germination.
- part of a flower, which is a kind of specialized structure that forms microspores and pollen. It consists of a filament, through which it is attached to the receptacle, and an anther containing pollen. The number of stamens in a flower is a systematic feature. Stamens are distinguished by the method of attachment to the receptacle, by shape, size, structure of the stamen filaments, connective tissue and anther. The collection of stamens in a flower is called the androecium.
Oak
forms the outer circle of the perianth; its leaves are usually relatively small in size and green in color. There are separate and fused calyx. Usually it serves the function of protecting the internal parts of the flower until the bud opens. In some cases, the calyx falls off when the flower opens; most often it remains during flowering.
Dioecious plants, plants in which male (staminate) and female (pistillate) flowers or male and female reproductive organs (in non-flowering plants) are not on the same individual, but on different ones.
Birch
Tomatoes (facultative self-pollination) - flowers have both pistils and stamens. The stamens are fused so that in most cases the pistil is fertilized by its own pollen.
Hazel
Male flowers (staminate) are located in the catkins of the plant, but female flowers (pistillate) are located in the flower buds. Hazel bushes are universal monoecious plants. Fruits, bark, leaves and even roots - all this is actively used in medicine. Varicose veins, constipation, lack of milk in nursing women, rickets, anemia, hypertension - all these problems can be easily dealt with by decoctions, tinctures, ointments and other products made from hazel components.
All plants known to science are divided into three groups - monoecious, dioecious and polyecious. In the former, heterosexual inflorescences are located on one individual, in the latter, on different ones. Moreover, the flowers themselves can be either bisexual - with pistils and stamens, or dioecious, which have either a pistil or a stamen. Polyecious plants provide for the presence of two varieties of inflorescences on one individual. So-called polygamy is observed in horse chestnut, ash, grapes, and forget-me-nots. But we are not talking about them now. This article tells you which plants are monoecious and provides a brief description of their brightest representatives.
Sedge
Living space!
DIOECOUS PLANTS, a group of plants in which male (staminate) and female (pistillate) flowers are on different individuals, for example poplar, hemp.
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There are dioecious and monoecious plants (it seems), but are there homeless plants?
UNESCO
Flowers are formed on the shoots. Very rarely they are located alone. Much more often, flowers are collected in noticeable groups called inflorescences. The study of inflorescences began with Linnaeus. But for him, the inflorescence was not a type of branching, but a way of flowering.
The pollen swells, and the restraining influence of the exine (the outer layer of the pollen grain shell) causes the contents of the pollen cell to rupture one of the pores, through which the intina (the inner, poreless shell of the pollen grain) protrudes outward in the form of a narrow pollen tube. The contents of the pollen cell pass into the pollen tube.
Filament
The parts of the flower located around the stamens and pistil are called the perianth.
Personal Account Removed
A flower is a conspicuous, often beautiful, important part of flowering plants. Flowers can be large or small, brightly colored and green, fragrant or odorless, solitary or collected together from many small flowers into one common inflorescence.
Marina Shestova
Poplar and sea buckthorn are dioecious plants: on male trees there are only flowers with pollen, and fruits are produced by female trees (in poplar in the form of fluff). If you grow only male poplars from cuttings, you can get rid of the fluff.
Impeler
rlrol
Andrey Yurkov
When listing monoecious plants, I would like to dwell on this herbaceous specimen. Today more than two thousand of its species are known. Sedge loves moisture very much, so it can most often be found in swamps. It can also grow directly in water. A prerequisite for its normal existence is the presence of light. However, the plant can easily adapt to semi-dark areas.
Many scientists believe that unisexual flowers were formed from bisexual ones, and this happened due to evolutionary processes. Speaking about monoecious plants, it is necessary to emphasize that they are characterized by the presence of pistillate or staminate inflorescences on one specimen. Representatives of both sexes are “in the same house” - hence the name of these green spaces.
gfsdh dhgdfhg
How does a man without a mistress differ from a man with a mistress?
Lyubov Lukyanova
Easy to remember: monoecious - husband and wife live together - in the same house; dioecious - in different houses.
What do monoecious plants have and what do dioecious plants have?
Akinfiy Dvinyatin
The inflorescences are distinguished between main and lateral axes (sessile or on peduncles); such inflorescences are called simple. If the flowers are on the lateral axes, then these are complex inflorescences.
Under the epidermis of the stigma there is loose tissue into which the pollen tube penetrates. It continues to grow, passing either through a special conducting channel between mucus cells, or tortuously along the intercellular spaces of the conductive tissue of the column. In this case, usually a significant number of pollen tubes simultaneously advance in the style, and the “success” of one or another tube depends on the individual growth rate.
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- the sterile part of the stamen, bearing an anther at its apex. The filament can be straight, curved, twisted, tortuous, or broken. Shape: hair-like, cone-shaped, cylindrical, flattened, club-shaped. The nature of the surface is bare, pubescent, hairy, with glands. In some plants it is short or does not develop at all.
The inner leaves are the petals that make up the corolla. The outer leaves - sepals - form a calyx. The perianth, consisting of a calyx and corolla, is called double. A perianth that is not divided into a corolla and a calyx, and all the leaflets of the flower are more or less the same - simple.
Olesya
A flower is a modified shortened shoot used for seed propagation. The main or side shoot usually ends in a flower. Like any shoot, a flower develops from a bud.
With sea buckthorn, you need to pay attention to the fact that only female bushes produce fruit, but if there is no male sea buckthorn bush nearby, then the female plant will not be able to produce fruit. Usually, for 10 female bushes, one male bush is enough.
apartment
The inflorescences are unisexual: male and female specimens have from 2 to 5 stamens and pistils. Sedge leaves reach one meter in height. They are tightly grouped, so they look more like hummocks that can easily support the weight of a person. They are very dense with hard edges, so it is not recommended for a person to tear them with bare hands: you can seriously cut yourself. Recently, the plant is increasingly used for decorative purposes - especially in areas where there are artificial reservoirs. Sedge decorates small lakes and ponds. Also, the plant is often used as feed, less often used in pharmacology.
Plants of this type are most often wind-pollinated. There are cases when pollen is carried by insects - this process is called entomophily. Plants are not characterized by autogamy, when pollination occurs in the cup of one flower. Most often, pollen enters the bosom here from other inflorescences located on the same plant. And this directly affects the properties of the seeds.
Apparently something was blown away!
Monoecious plants are plants in which male and female flowers are located on the same individual.
in monoecious plants both maternal and paternal flowers are in the same plant
Two sperm and one vegetative nucleus pass into the pollen tube. If the formation of sperm cells in pollen has not yet occurred, then a generative cell passes into the pollen tube, and here, through its division, sperm cells are formed. The vegetative nucleus is often located in front, at the growing end of the tube, and sperm are successively located behind it. In the pollen tube, the cytoplasm is in constant motion.
Anther
Corolla
A flower is the reproductive organ of angiosperms, consisting of a shortened stem (flower axis), on which the flower cover (perianth), stamens and pistils, consisting of one or more carpels, are located.
What does dioecious plant mean? What kind of plants are dioecious plants? Please give examples and explain why?!
Irina Ruderfer
Corn is a monoecious plant with unisexual flowers. Male flowers are collected at the top with a panicle, female flowers - on the trunk with cobs. Also monoecious plants with unisexual flowers are pumpkins - cucumbers, pumpkins, etc. They have flowers of different types growing on the same plant, although they are not so different in appearance. But the male flowers die and fall off after pollination. From the female fruits grow.
(dioecious people rent one)
This division applies to flowering plants. Can flowers be homeless? But they can be three-housed:
Tugeus Vladimir
Monoecious plants are found at every step. Examples of such green spaces are the following: watermelon, corn, pumpkin, walnut, hazel, alder, beech, birch and oak. There are also known species that, under extreme conditions, can transform from dioecious to monoecious - these include, for example, hemp.
Borisovna
at least in the answers I’ll remember what it is))))))))))))
Accordingly, dioecious, on different individuals or plants.
Andrey Yurkov
for dioecious ones separately
Flower
Pollen is rich in nutrients. These substances, especially carbohydrates (sugar, starch, pentosans) are intensively consumed during pollen germination. In addition to carbohydrates, the chemical composition of pollen includes proteins, fats, ash and a large group of enzymes. Pollen contains a high phosphorus content. Substances in pollen are in a mobile state. Pollen easily tolerates low temperatures down to – 20Cº and even lower for a long time. High temperatures quickly reduce germination.
located at the top of the filament and attached to it by a connective tissue. It consists of two halves connected to each other by a connector. Each half of the anther has two cavities (pollen sacs, chambers, or nests) in which pollen develops.
Flower structure
- the inner part of the perianth, differs from the calyx in its bright color and larger size. The color of the petals is due to the presence of chromoplasts. There are separate and fused corollas. The first consists of individual petals. In fused-petal corollas, a tube is distinguished and a limb located perpendicular to it, which has a certain number of teeth or corolla blades.
The axis of the flower is called Information on the topic here http://ru.wikipedia.org/ Dioecy is the main way of modern plants to prevent self-pollination; female and male flowers in this case are on different individuals (“in two houses”). This method is effective, but half of the population in this case does not produce seeds. Dioecious plants include : willow, stinging nettle, laurel, sea buckthorn, mistletoe, aspen, asparagus, poplar.
Monoecious plants are plants of the same species with bisexual or unisexual flowers (bearing either only pistils or only stamens), but developing on one individual. Monoecy is common among both anemophilous (wind-pollinated) and zoophilous (animal-pollinated) plants. Examples of monoecious plants: oak, birch, pumpkin, walnut, etc.
One of the brightest representatives of monoecious plants. It is rich in vitamins, alkaloids, carotene, essential oils, iron salts and other beneficial substances. Walnut improves memory, helps get rid of constipation, is essential for heart disease and diabetes, and prevents the appearance of breast and prostate cancer. In dioecious plants, the stamens and pistils (maternal and paternal reproductive organs) are divided into different flowers, sometimes even into different plants. For example, SEA BUCKTHORN should be planted on 3-5 mother bushes and one father bush. And in monoecious plants, both pistils and stamens are located in one flower.1 - one husband
Monoecious plants are plants that have unisexual flowers - male (staminate) and female (pistillate) - on the same plant. Examples: birch, hazel, oak, pine, spruce, corn, pumpkin. The pistil is the part of the flower that forms the fruit. It arises from the carpel (a leaf-like structure bearing ovules) subsequently fusion of the edges of the latter. It can be simple if it is made up of one carpel, and complex if it is made up of several simple pistils fused together with side walls. In some plants, the pistils are underdeveloped and are represented only by rudiments. The pistil is divided into an ovary, a style and a stigma.
As a rule, the anther is four-locular, but sometimes the partition between the nests in each half is destroyed, and the anther becomes two-locular. In some plants the anther is even single-lobed. Very rarely found with three nests. Based on the type of attachment to the filament, fixed, movable and oscillating anthers are distinguished.
Flowers can be symmetrical or asymmetrical. There are flowers that do not have a perianth; they are called naked.
receptacleOr here http://go.mail.ru/ Type in Monoecious and dioecious plants
Monoecy - female and male flowers are on the same individual (“in the same house”). More often found in wind-pollinated plants. Monoecy eliminates autogamy (pollination of the stigma with pollen of the same flower), but does not protect against geitonogamy (pollination of the stigma with pollen of other flowers the same individual). Monoecious plants include: watermelon, birch, beech, walnut, oak, corn, hazel, lemongrass, cucumber, alder, pumpkin, breadfruit.
Dioecious plants are plants with unisexual flowers that develop on different individuals (on a male or female plant, respectively). Unisexual flowers appeared in the process of plant evolution much earlier than bisexual flowers, and dioecy can be considered as an adaptation to anemophily (wind pollination), since it is in this case that the greatest probability of cross-pollination is achieved. Examples of dioecious plants: aspen, poplar, willow, sorrel, stinging nettle, sea buckthorn.Begins to bloom in May. The healthy fruits of the tree can be enjoyed as early as September. Walnut inflorescences are collected in small groups - from two to five pieces. Due to the fact that male and female flowers do not ripen at the same time, cross-pollination occurs between them. Nut fruits can set without pollination, but then their properties will be of very poor quality.
Some have a villa.. others have a 2-storey cottage..))2-one husband + one lover
OvaryThe anthers contain pollen or pollen grains.
Symmetrical (actinomorphic). The receptacle, growing, takes on various shapes: flat, concave, convex, hemispherical, cone-shaped, elongated, columnar. The receptacle below turns into a peduncle, connecting the flower with the stem or peduncle.
Dioecious plants are plants whose dioecious (or unisexual) flowers are located on different specimens of the same plant species, i.e. on one plant all the flowers are only pistillate or fruiting (female), and on another specimen. of the same species, they are all only staminate (male, non-fertile, early shedding). Plants that develop dioecious flowers on the same individual are called monoecious; In dioecious plants, female and male flowers appear on different specimens of the same species.
Triecious plants are plants that produce three types of flowers: male (staminate), female (pistillate) and bisexual (have both stamens and pistils), developing on different individuals. Triecious plants are much less common in nature compared to monoecious and dioecious plants. An example is some types of resins - plants from the clove family.
Trees of the beech family are also monoecious plants. Oak is a typical representative of them. It has long been considered the personification of wisdom, durability, beauty and strength. The bark, leaves, and acorns of the plant have similar qualities. They are very strong and can withstand winter frosts and summer heat, bad climatic conditions and sudden changes in weather. The height of the oak tree is no more than 30 meters, although real giants are often found in nature. Few people know that the oak tree begins to bear fruit only after thirty years from the moment of planting.
Pollen grain structure
One house is good, but two are better!
These are pollinated and these are not!!.
Monoecious plants are plants that have unisexual flowers - male (staminate) and female (pistillate) - on the same plant. Examples: birch, hazel, oak, pine, spruce, corn, pumpkin.
- the lower part of the pistil, which contains the seed germs.
Pollen germination
The dust particles formed in the anthers of the stamens are small grains, they are called pollen grains. The largest ones reach 0.5 mm in diameter, but usually they are much smaller. Under a microscope you can see that dust particles from different plants are not at all the same. They differ in size and shape.
- if many axes of symmetry can be drawn through the rim.
Flowers that do not have a peduncle are called sessile. On the peduncle of many plants there are two or one small leaves - bracts.
The best examples of such plants are all willows (Salix) and poplars (Populus), hemp, nettles, some species of cloves and many others, for example. Vallisneria, watercolor.
Types of pollination
There are lobed and dicotyledonous...
Pestle
The oak tree bears both female and male flowers, so these trees are monoecious plants. Staminate individuals are usually collected in small inflorescences and have a greenish color. Their top is decorated with a raspberry edging. There are fewer male flowers - they are arranged “in one bunch” of three and have a pleasant pale pink color. A lot is known about the healing properties of oak. To produce healing drugs, everything is used - bark, acorns, leaves, which have wound-healing, astringent, and anti-inflammatory properties. Oaks grow well in any climatic conditions: both in damp swamps (Virginian species) and in dry areas.
The fact that dioecious can become triecious if... they won't hit you in the head with a frying pan in time)))the first ones don’t have a mother-in-law
Dioecious plants are those in which fertile (female) flowers and sterile (male) flowers are located on different individuals. These are, for example, willows and poplars.
Flowers regular and irregular
Having entered the ovary, the pollen tube grows further and enters the ovule in most cases through the pollen duct (micropyle). Invading the embryo sac, the end of the pollen tube bursts and the contents spill onto one of the synergids, which darkens and quickly collapses. The vegetative nucleus is usually destroyed before the pollen tube penetrates the embryo sac.
Flowers bisexual and dioecious
The surface of the dust particle is covered with various protrusions and tubercles. Once on the stigma of the pistil, pollen grains are held with the help of outgrowths and sticky liquid released on the stigma.
Monoecious and dioecious plants
Asymmetrical (zygomorphic)
Flower cover -
Inflorescences
They are contrasted with monoecious plants - plants also with dioecious flowers, but always located on the same plant (cucumbers, pumpkins, birch, alder, all conifers, and many others). All dioecious plants constitute a special 21st class in Linnaeus’ system, but in the newest natural systems they no longer remain in one general group, but are distributed among the most diverse families and genera, both dicotyledons and monocotyledons. Self-pollination in dioecious plants is unthinkable. Being separated from the male specimens by females, often at considerable distances, they naturally require intermediaries to facilitate cross-pollination; such intermediaries are wind for trees, insects for small herbaceous forms, and water flow for aquatic species.
There are two main types of pollination: self-pollination - when the plant is pollinated by its own pollen - and cross-pollination.
biouroki.ru
How do MONOECIOUS plants differ from DIOECIOUS plants????
MGazov
Homeless is when they are put on the landing:((
Monoecious plants include not only walnut and oak, but also birch. The components of the tree are often used in folk medicine. For example, tincture of kidneys is actively used by healers to eliminate various diseases. And birch mushroom restores strength well. It effectively neutralizes headaches and increases appetite. And everyone’s favorite birch sap perfectly cleanses the body, fights against the formation and growth of internal tumors.
Nastyusha
Some have a house in the village, others have a two-story villa in the Canary Islands)
Some plants have one home! The rest have two!
Andrey Yurkov
Nostalgia. The second home can be anywhere, the place of the first is in childhood. Sore throat, first love, school, botany - push her into a swing
The tepals (single and double) can be arranged so that several planes of symmetry can be drawn through it. Such flowers are called regular. Flowers through which one plane of symmetry can be drawn are called irregular.
How do monoecious plants differ from dioecious plants?
Avigdor Bern
The nests of young anthers contain special diploid cells. As a result of meiotic division, four haploid spores are formed from each cell, which are called microspores due to their very small size. Here, in the cavity of the pollen sac, microspores turn into pollen grains.
Gleb Rustinok
– if only one axis of symmetry can be drawn.
One of two
perianth
Helen Helen
In which “fathers” and “mothers” grow separately, for example, nettles
When cross-pollinated, plants can produce two main types of plants: monoecious and dioecious.
Of course there are!! ! Take one monoecious or dioecious plant and quickly cut off all the flowers with all their contents. . All!! no home anymore)))
ku?!
Birch can reach a height of up to twenty-five meters. It is slightly inferior to the beech family in terms of the number of genera and species. And significantly. There are only 150 species of the birch “clan”; for beech trees this figure is significantly higher - 800 species. Almost all representatives of the birch family are resistant to frost, only Japanese, Chinese and Himalayan individuals are not included in them.
Dioecious plants are plants with unisexual (male or female) flowers that are not on the same individual, but on different ones; (e.g. nettle, willow, hemp).
Dioecy- the main way of plants to prevent self-pollination; female and male flowers are on different individuals (“in two houses”). This method is effective, but half of the population (male) in this case does not produce seeds. Dioecious plants include: willow, laurel, lemongrass, sea buckthorn, mistletoe, aspen, asparagus, poplar, hemp, pistachio, ginkgo.
Monoeciousness- female and male flowers are on the same individual (“in the same house”). More often found in wind-pollinated plants. Monoecy eliminates autogamy (pollination of the stigma with pollen of the same flower), but does not protect against geitonogamy (pollination of the stigma with pollen of other flowers of the same individual). Monoecious plants include: watermelon, birch, beech, walnut, oak, corn, hazel, cucumber, alder, pumpkin, breadfruit.
Other types of gender distribution:
- andromonoecy- male and bisexual flowers are on the same individual
- gynomonoecy- female and bisexual flowers are on the same individual
- androdiecy- male and bisexual flowers are on different individuals
- gynodiecy- female and bisexual flowers are on different individuals
- trietius, or three-household- bisexual, female and male flowers are on different individuals.
About 75% of flowering plant species have bisexual (hermaphroditic) flowers, and only about 25% of flowering plant species have dioecious flowers.
Individuals of some dioecious plants, such as hemp, under certain stressful conditions can produce flowers of both sexes, that is, become monoecious.
Flower formula and diagram
The formula of a flower represents a symbol of its structure using letters of the Latin alphabet, symbols and numbers .
When drawing up the formula, use the following notation:
P – perianthium;
Ca (or K) – calyx (calyx);
Co (or C) – corolla (corolla),
A – androecium (androeceum),
G – gynoecium (gynoeceum).
The * sign placed before the formula indicates the actinomorphy of the flower; sign – for zygomorphy. A staminate flower is indicated by the sign; pistillate – bisexual with a combined sign. The “+” sign indicates the arrangement of flower parts in two or more circles, or that the parts separated by this sign are opposed to each other. The brackets mean the parts of the flower are fused together.
The number next to the symbol indicates the number of parts (members) of this type in the flower. A line under the number indicating the number of carpels in the gynoecium, for example 3 , indicates that the ovary is superior; the line above the number is the inferior ovary; the line from the number is the semi-inferior ovary. A large and indefinite number of members is indicated by a sign.
For example, the formula for a tulip flower *P 3+3 A 3+3 G (3) shows that it is actinomorphic, has a simple six-membered perianth, the free lobes of which are arranged three in two circles; the androecium is also six-membered, consisting of two circles of stamens, and the gynoecium is coenocarpous, consisting of three fused carpels (compound pistil), forming the superior ovary.
Dandelion flower formula ↓ C a 0 Co (5) A (5) G (2) indicates that its flowers are zygomorphic, bisexual, have a double perianth, in which the calyx is reduced, the corolla consists of five fused petals, the androecium - of five stamens stuck together by anthers, and the gynoecium - of two fused carpels, forming the lower ovary. For the dandelion flower formula, a more rational notation G (1) is also acceptable.
Rice. thirty. Flower diagram. 1 – shoot axis, 2 – bract, 3 – sepal, 4 – petal, 5 – stamen, 6 – carpella, 7 – leaf
A flower diagram represents a conventional schematic projection of the parts of a flower onto a horizontal plane (Fig. 30).
Inflorescences. Classifications
Inflorescence - part of a shoot or a system of modified shoots bearing flowers. The biological meaning of inflorescences is the increasing likelihood of flower pollination. An insect will visit many more flowers per unit of time if they are collected in inflorescences. In addition, flowers collected in inflorescences are more noticeable among the green leaves than single flowers. Many inflorescences sway easily under the influence of air movement, thereby facilitating the dispersal of pollen.
Any inflorescence has a main axis and lateral axes, which can be branched to varying degrees or not branched (Fig. 31). The axes of the inflorescence are divided into nodes and internodes. At the nodes of the inflorescence axes there are leaves and bracts - modified leaves.
Rice. 31. Inflorescence structure: 1 – main axis, 2 – lateral axis, 3 – nodes, 4 – internodes, 5 – bracts, 6 – pedicels, 7 – flowers
Inflorescences in which the lateral axes branch are called complex . In simple inflorescences, the lateral axes are not branched and are pedicels. Simple inflorescences arose in the process of evolution from complex ones, which is associated with the reduction of their lateral axes. In bisexual plants, the inflorescences bear bisexual flowers, but in monoecious and dioecious plants the inflorescences can also be staminate, pistillate and polygamous. In the latter case, staminate, pistillate and bisexual flowers are found simultaneously.
Classification of inflorescences
- botryoid (bothrical, or racemose) - monopodial branching;
- cymoid (cymose) – sympodial branching.
1) Botrioid inflorescences (Fig. 32)
- brush(flowers sit on pedicels evenly distributed along the axis) (representatives of the cruciferous family).
- ear- a derivative of the raceme, which has sessile flowers (orchis ( Orchis);
- earring(poplar Populus, willow Salix);
- cob with a thickened inflorescence axis;
There are a number of inflorescences with a shortened axis - umbrella, head and basket.
- umbrella- an inflorescence derived from a raceme, in which all the pedicels and bracts are located at the top of the shortened axis of the inflorescence (primrose ( Primula), ginseng ( Panax). - head is a modified umbrella in which the pedicels are reduced, and the shortened axis of the inflorescence grows;
- basket- this is a head surrounded by an involucre, that is, close apical leaves (family Asteraceae).
- panicle- branched inflorescence with a gradual decrease in the degree of branching of the lateral axes from the base to the apex;
- complex shield(modified panicle with shortened internodes of the main axis and highly developed internodes of the lateral axes).
- antela- an inflorescence in which the internodes of the lateral axes are greatly elongated and the flower ends up at the bottom of the funnel formed by the lateral branches.
- complex brush- an inflorescence in which the botryoid inflorescences are simple racemes.
- double And triple compound brushes(derived from a complex raceme - a complex spike, in which sessile flowers are located on the lateral axes and the inflorescences are simple spikes);
- double and triple compound spike(most grasses and many sedges);
- complex umbrella(representatives of the umbrella family), which has lateral axes of two orders - first and second.
In addition to the listed inflorescences, there are a number of types in which the branching features of the main axis differ from the branching features of partial inflorescences - they are called aggregate(panicle of umbrellas - Aralia Manchurian Aralia mandshurica, panicle of baskets, raceme of baskets (row drooping Bidens cernua), ear of baskets (forest dried grass Gnaphalium sylvaticum) (rice. 32).
Rice. 32. Types of botryoid inflorescences. A – simple botryoid: 1 – brush, 2 – ear, 3 – ear, 4 – simple umbel, 5 – head, 6 – basket, 7 – scutellum (4. 5, 6 – with a shortened main axis, others – with an elongated one) ; B – complex botryoid.
Panicle and its derivatives: 1 – panicle, 2 – complex scutellum, 3 – antelela; B – complex botryoid. Complex brush and its derivatives: 1 – triple brush, 2 – double brush, 3 – double spike, 4 – double umbrella
Rice. 33. Aggregate inflorescences: 1 – panicle of umbrellas, 2 – panicle of baskets, 3 – shield of baskets, 4 – raceme of baskets, 5 – spike of baskets
1) Cymoid (cymose) inflorescences: cymoids and thyrsi .
Rice. 34. Cymoid inflorescences. A – cymoids: 1-3 – monochasia: 1 – elementary monochasia, 2 – gyrus, 3 – whorl, 4 – double whorl, 5-6 – dichasia: 5 – dichasia, 6 – triple dichasia, 7-8 – pleiochasia: 7 – pleiochasium, 8 – double pleiochasium; B – thyrsus
1) Cymoids- These are simplified thyrsi with sympodial branching. There are three types of cymoids: monochasia, dichasia and pleiochasia.
- monochasia- under the flower that completes the main axis, only one inflorescence or a single flower develops (gyrus, curl and ball) (ranunculaceae, borage).
- dikhazia- from the main axis, under its final flower, two partial inflorescences extend, and in the simplest cases, two flowers.
Simple, double, triple dichasias are possible. Dichasia is found in a number of carnation plants, for example species of the genus Chickweed ( Stellaria).
- pleiochasy- under the flower that completes the main axis, three or more partial inflorescences (or flowers) develop. Double, triple and more complex pleiochasias are fundamentally possible.
2) Thyrsae are more complex than cymoids. These are branched inflorescences, in which the degree of branching decreases from the base to the apex.
The main axis of the thyrsus grows monopodially, but the partial inflorescences of one order or another are cymoids. For example, thyrsus is the inflorescence of horse chestnut ( Aesculus hippocastanum), another example of thyrsus is the mullein inflorescence ( Verbascum) from the Norichnikov family. Thyrses of various types represent inflorescences of all Lamiaceae. The inflorescence of birch is an earring-shaped thyrsus.
All plants, without exception, known to science are classified into three groups - monoecious, dioecious and polyecious. In the first, heterosexual inflorescences are located on the same plant, in the second - on different ones. Moreover, the flowers themselves can be either bisexual - with pistils and stamens, or dioecious, which have either a pistil or a stamen. Polyecious plants provide for the presence of two varieties of inflorescences on one plant. So-called polygamy is observed in horse chestnut, grapes, forget-me-nots, and ash.
Picture 1.
Characteristics of monoecious plants
Note 1
Many scientists believe that unisexual flowers arose from bisexual ones, and this happened as a result of evolutionary processes. Monoecious plants are characterized by the presence of pistillate or staminate inflorescences on one individual. Flowers of both sexes are “in the same house” - hence their name. The flowers of some plants do not have a formed perianth. This type of plant is predominantly wind pollinated, but there are cases when they are pollinated by insects - this process is called entomophily. Plants can self-pollinate, this is when pollination occurs in the cup of one flower. Most often, pollen enters the bosom from other inflorescences located on the same plant. And it has a bad effect on the properties of seeds. Monoecious plants are very common. For example, corn, alder, watermelon, beech, pumpkin, walnut, hazel, birch and oak. In addition, there are species that reorganize from dioecious to monoecious under stressful conditions - for example, a plant such as hemp.
Walnut is one of the brightest representatives of monoecious wind-pollinated plants. Bees visit only male flowers and ignore female ones, for this reason their importance in pollination is negligible. The difference in the blooming of male and female flowers on the same plant reaches $15$ per day. As a result, cross-pollination occurs.
Hazel is a monoecious plant. Male flowers are in drooping earrings, female flowers are hidden inside the buds, only crimson stigmas protrude. Pollinated by wind. The fruit of hazel is a brown-yellow single-seeded nut, surrounded by a bell-shaped plus of modified bracts. Hazel bushes are a universal monoecious plant.
Characteristics of dioecious plants
In dioecious plants, female and male flowers grow on different plants of the same species, so they may differ in external characteristics. This is, for example, like a rooster and a hen. For the fertilization process, cross-pollination is necessary, that is, the transfer of pollen from the anthers of male flowers to the stigmas of female flowers. In this they are helped to attract insects, which plants of this species have large and colorful flowers. Such pollination is considered more perfect, as it helps strengthen the species. Most fruit trees require both sexes. One male flower serves to pollinate several female flowers. And only after this can fruits form on the female flowers. But it is not necessary to have one plant of the opposite sex for each female plant; one male representative can pollinate a number of females. The number depends on the type of green space. For example, a whole grove of date palms is fertilized by several male trees. One is enough to pollinate about $40-50$ of palm trees. Sometimes, for better and more successful pollination, a branch of a male tree is grafted onto female trees.
Note 2
For practical purposes, it is important not only to know which plants are dioecious, but also to be able to distinguish the sexes of individuals of the same species. In representatives of the same species, sex is initially difficult to determine. If we consider the structure of a male and female flower, we note that the male flower has an underdeveloped stigma or no stigma at all, but its stamens are strewn with pollen. In turn, the female flower is devoid of stamens, or if there is a stamen, then it has very little pollen. This knowledge is important for gardeners. For example, if there is a tree in the garden that does not bear fruit, then it is probably dioecious, and it is necessary to determine its sex and plant a tree with the opposite sex on the site. Or graft a twig from another individual of this species onto it. Well, if you need to decorate an ornamental garden or personal plot, we choose a dioecious tree of the same sex, so that overripe fruits do not spoil the aesthetics, and there is no need to constantly clean the area.
Dioecious male plants produce large amounts of pollen, since the female tree may not be nearby. Therefore, there must be a lot of pollen so that some percentage reaches the stamens of the far-growing female. The pollen is very light and has a shape that allows it to float in the air.
Let's consider a dioecious plant using the example of figs. Fig flowers are small and inconspicuous. Only female plants bear fruit. Figs are pollinated only with the help of a blastophagous wasp. In order for the female wasp to become fertilized, she looks for male fig flowers, since her wingless prince sits there. Once fertilized, inside the flower on her belly, she collects pollen from the male flower. Once fertilized, it climbs out in search of a new flower, and thus transfers pollen to the stamens of female flowers.
Among dioecious plants, there are forms in which it is impossible to determine the difference between the sex chromosomes. For example, hemp. In extreme situations, it is capable of turning from a dioecious plant into a monoecious plant; breeders also breed it as a monoecious plant. In some dioecious flowering plants, forms with intermediate male and female individuals have been observed. Thus, the mechanism of sex determination is currently unclear.
Hemp that bears male flowers is called poskonyu, or habit. Female hemp is called materka. The mother plant is thicker-stemmed, leafy and tall. The mother material matures later. The edges dry out quickly, almost immediately after flowering. For sowing hemp, female and male specimens are taken in a ratio of $1:1$. But despite this, the harvest is different. The mater reproduces a third of the total fiber harvest.
Note 3
In dioecious plants, specific sex chromosomes are found, similar to those in animals. For the first time in 1917, Allen identified sex chromosomes in the liver moss plant. It is known that moss plants are always haploid, while the sporangium and its stalk are diploid. Allen discovered that male moss plants have $7 regular chromosomes and one small Y chromosome. The female plant has 7 Y chromosomes and one very long X chromosome.
During fertilization, these two sets of chromosomes combine to form a sporophyte with the set $14A+X-b Y.$ At the meiosis stage, seven pairs of autosomes and one pair $X Y$ are formed. It follows that half of the spores will receive the set $7A+X$, and the other half will receive $7A+Y$. From these spores the male and female spores of a given species directly develop.
Today, breeders are able to shift the sex of plants. It is quite possible to change the number of female flowers in cucumber and spinach by treating the plants on the eve of flowering with carbon monoxide, ethylene or other reducing agents. Under the influence of mineral nutrition conditions, photoperiodicity and temperature conditions, the ratio between the number of male and female generative organs (flowers) shifts significantly.
Unisexual plant species are those in which flowers of both sexes are located on the same tree or shrub, therefore they are also called bisexual species. Sometimes there are polygamous cultures that have male bisexual and unisexual flowers simultaneously on a single individual.
Monoecious species, in which flowers of two sexes grow at once, are very common in nature.
Examples of monoecious plants
Hazel
Watermelons
Hazel
Birches
Corn
Walnuts
Pumpkin crops
Flowers of plants with monoecy
Monoecy is a special adaptation, which consists in the fact that flowers of both sexes live in the same “house”. On one tree or shrub there are both staminate and pistillate inflorescences. Sometimes there are flowers whose perianths are not fully formed. In this case, the pollen is well dispersed by the wind over long distances, and it is carried by bees, but their main advantage is that they have a self-pollinating mechanism (entomophily), and therefore do not depend on external factors. This happens when pollination occurs in one flower: pollen from one inflorescence falls on another. It is worth noting that in stressful situations for plants, they turn into monoecious. This phenomenon is observed in hemp.
How does pollination of monoecious plants occur?
Different species with monoecy have their own pollination characteristics. To do this, it is better to consider several examples. Thus, the walnut is considered a wind-pollinated tree. The fact is that bees land only on male inflorescences, and do not visit female inflorescences, so insects take practically no part in the pollination of walnut flowers. This also happens because male and female flowers do not bloom on the tree at the same time. In this regard, the inflorescences are pollinated due to wind activity.
Hazel has an interesting pollination mechanism. This is a genus of shrubs and trees (in rare cases) in which the male flowers are in catkins and the female flowers are in the middle of the buds, so they are not so easy to reach. Pollination occurs thanks to the wind.
Thus, in nature, the most common mechanism is monoecy, when both male and female flowers grow on the same plant. This gives plants a much better chance of pollination. First, bees do not need to fly long distances to transport pollen from male flowers to female flowers. Secondly, if insects take little part in the pollination process, then the wind will always scatter the pollen, and it will fall from the male flowers to the female ones, which will subsequently ensure the appearance of fruits.
