I, the basic structure and types of flowers A complete flower is composed of calyx, corolla, stamens and pistil and other parts **** with the adherence to the receptacle. In the long-term evolutionary process, and in different environments, the flower parts of the various morphological variations, the formation of a variety of forms, colorful and colorful world of flowers. Morphological characteristics of flowers are one of the important bases for the classification of angiosperms, as well as for the study of the affinities between plants of different families and genera. In this experiment, through the observation of peach blossom (Prunus persica) and other typical plant flowers, we will understand the basic structure of flowers and different types of flowers. (I) The basic structure of flower - observation of peach blossom Peach blossom is a solitary flower with a stalk and a bract under each flower. Take a fresh or soaked peach blossom, and first observe the number, form and attachment of the calyx, corolla, stamens and pistils layer by layer from the outside in. Then cut the peach blossom along the longitudinal direction and make further observation under the solid anatomical microscope. The receptacle of peach blossom is cup-shaped, i.e. the middle of the receptacle is concave into a small cup. The sepals, petals and stamens are inserted at the edge of the cup-shaped receptacle, and the ovary of the pistil is inserted at the depressed part in the center of the receptacle. The calyx of the peach blossom consists of five green leaf-like sepals, each sepal free from the other. The calyx is also called the outer perianth. The corolla of peach blossoms consists of five pink petals, free. The corolla is also called the inner perianth. Peach blossoms have an indefinite number of stamens. Each stamen consists of filaments and anthers two parts, filaments play a support and contact role, anthers can produce pollen grains, the main part of the stamens. Stamens in the edge of the receptacle for the whorl arrangement. Peach blossom pistil is bottle-shaped, can be divided into stigma, style and ovary three parts, ovary bearing ovules. The ovary of the peach blossom is only attached to the base of the receptacle, while the other parts are separated from the receptacle, so its attachment position is the superior ovary. The calyx and corolla of the peach blossom are inserted on the edge of the cupular receptacle, and their position relative to the ovary is perigynous (Fig. 38-1). The above observations show that the peach blossom has a full complement of floral parts and is a typical perfect flower, a double perianth with an outer perianth (calyx) and an inner perianth (corolla), a bisexual flower with stamens and pistils, and a neat flower with an actinomorphic corolla. The structure of peach blossom can represent the basic structure of flowers in general. (ii) Types of flowers 1. Complete and incomplete flowers Complete flowers refer to a flower with complete calyx, corolla, stamens and pistils. When any one or two or even three of these four parts are missing from the structure of the flower of some plants, it is an incomplete flower. When the inner or outer whorl of the perianth is missing, a unipetalous flower can be formed, and when the perianth is completely missing, a naked flower is formed. Unisexual flowers are formed when either stamens or pistils are missing, and neutral or asexual flowers are formed when both pistils and stamens are missing. Heavy perianths, single perianths, and rudimentary flowers Heavy perianths, such as the peach blossom, have both a calyx and a corolla (Fig. 38-2, A); single perianths, as observed in hydrangea macro_phylla, have only one perianth whorl, lack a corolla, and have petal-like sepals. In general, single perianth flowers mostly lack a corolla (Fig. 38-2, B); naked flowers, observing the male flowers of Populus, it can be seen that each male flower is composed of 6-8 stamens inserted in a cup-shaped disk, with neither calyx nor corolla outside, and only a bract. Both female and male flowers of poplar (Populus) and willow (Salix) are naked (Fig. 38-2, C). Bisexual, Unisexual, and Neutral Flowers Amphoteric flowers, such as peach blossoms, have both stamens and pistils; unisexual flowers, such as poplars or willows are unisexual, with male flowers lacking pistils and female flowers lacking stamens. Others, such as cucumber (Cucumis sativus), corn, etc., also with unisexual flowers; neutral flowers, Asteraceae sunflower head of the side flowers or carrot umbels peripheral flowers, only perianth, and female and male stamens do not develop, for the neutral flower, or asexual flowers. 2. neat flower and not neat flower neat flower and not neat flower division is mainly based on the symmetry of the corolla. Neat flower corolla is radial symmetry, through the center of the flower can be divided into a number of symmetry; not neat flower corolla symmetry, through the center of the flower can only be divided into a symmetry. Neat flower - cotton (land cotton) observation Cotton is also a complete flower, neat flower, observation should pay attention to its morphological differences with peach blossom. Take the flower of a fresh or soaked cotton and observe the morphology of the calyx, corolla, stamens and pistil layer by layer from the outside to the inside. Notice that the outermost layer of the cotton flower has three leaf-like structures enclosing the entire flower, which are three large bracts, also known as the epicalyx. Turn over the epicalyx to see five united sepals just outside the corolla at the base of the flower. The petals are five in number, separated and arranged in an imbricate pattern. Cotton stamen structure is more special, the number of stamens, the filaments of each stamen base united into a stamen tube, the style of the pistil partially surrounded by the base of the stamen tube and the petals combined, while the filaments of each stamen and the anthers are separated from each other. This type of stamen of cotton is specifically called a single stamen. Peeling off the stamen tube can be seen in the cotton pistil, bottle-shaped, by 3-5 carpels combined, stigma slightly separated. Finally, the cotton receptacle is seen to be flattened and the ovary is superior. The corolla of cotton is radially symmetrical, and multiple planes of symmetry can be delineated through the center of the flower (Fig. 38-3, A). Untidy Flowers-Observations on Pea Flowers Pea flowers are perfect flowers, but the corolla is symmetrical on both sides, making them untidy flowers. Take a fresh or soaked pea flower for observation. Pea flowers are also five counted flowers. The outermost whorl has sepals of five united. Its corolla structure is peculiar, the five petals are not uniform in form, the outermost petal wrapped in the outermost whorl is larger, a flag petal, inwardly there is a winged petal on the right and left, and in the center there are two keeled petals, which are smaller, and slightly united on the lower edge. This type of corolla is called the butterfly corolla. The pistils and stamens of the pea flower are enclosed in the keel petals. There are 10 stamens, 9 of which have partially united filaments and separate anthers, and the other stamen is separate, this type of stamen is called amphistamen. The pistil is enclosed in the united filaments, united by a carpel, the ovary is longer, bearing a number of ovules on the ventral suture line. The pea flower corolla is bilaterally symmetrical and can only be drawn through the center of the two keeled petals, a plane of symmetry, for an untidy flower (Fig. 38-3, B). 3. Observations of Gramineae Glomerules-Wheat Florets The parts of the gramineae flower are highly specialized and have a more specific structure, and are specifically called glomerules. Observe the structure of wheat florets to understand the characteristics of glume structure. Observation of wheat glumes. The entire wheat spikelet is a compound spike, which is composed of a number (usually more than ten to twenty) of spikelets inserted on the rachis. Each spikelet is a spike, consisting of several (three, five or more) sessile florets borne on the rachilla. The spikelet has a pair of glumes at the base. The florets are arranged in alternate rows on the rachilla, and generally the top floret is incompletely developed as a sterile flower (Fig. 38-4, A, B). The specific structure of a glume in wheat is observed by taking a well-developed floret at the base of the spikelet and peeling off the components of the flower sequentially from the outside to the inside. A wheat glume consists of the following structural parts: a lemma, with its veins conspicuous, and sometimes the tip of the lemma may extend into an awn; a palea, thinly membranous, boat-shaped, with two conspicuous lateral veins; and two plasma lamellae, which are a pair of small thin membranous lamellae immediately adjacent to the base of the ovary on the side opposite to the lemma. The plasma sheet is related to the opening of the floret, when wheat blooms, the plasma sheet rapidly absorbs water and expands, holding the palea and lemma open, facilitating the extension of the stamens and the pistil stigma to bear pollen; wheat has three stamens, when flowering, the filaments elongate rapidly, pushing the anthers out of the palea and lemma, the anthers longitudinal cleavage dispersal of pollen; the pistil is a pistil, composed of the two carpels united, the stigma two-lobed and feathery, the style is short, inconspicuous, and the ovary is dilated to a globular shape. (Fig. 38-4, C, D). The basic structure of the graminaceous floret is as above. Sometimes certain parts of the structure differ, as in rice, where the stamens are six, arranged in two whorls of three each. The various parts of the floret are more specialized, and from the point of view of evolution, it is generally believed that the lemma of the floret is equivalent to the bracts of each flower; the boat-shaped palea may be understood to be formed by the merging of two tepals of the outer whorl of the perianth, with the other tepal degenerated; and the plastron may have evolved from the two tepals of the inner whorl of the perianth, with the other tepal possibly degenerated as well. Therefore, the flower of wheat can still be understood as a ternary flower of monocotyledonous plants, only the parts of the flower are highly specialized. The morphology is highly variable. II. Morphological variation of receptacle and perianth In experiments XXXVII and XXXVIII, combined with the dissection of typical flowers, the systematic origin and basic structure of flowers have been observed and understood, and the division of flower types has been introduced. The following two experiments will be divided into two, mainly combined with physical specimens, wall charts and model observations, to provide a further introduction to the morphological variation of different parts of the flower, and certain evolutionary trends, as well as to illustrate the terminology related to the various words of morphology. This experiment first introduces the types of variation in the receptacle, calyx and corolla. (I) Morphological variation of the receptacle The receptacle is the attachment site of the calyx, corolla, stamens and pistil, and is a metamorphosis of a segment of the stem. From experiments 37 and 38 on the magnolia, buttercup, peach and pea four kinds of flowers in the observation, has seen the receptacle has a variety of different shapes. From the phylogenetic point of view, the morphology of the receptacle has evolved in a certain direction. That is, from the more primitive columnar receptacle, and then the receptacle shortened to hemispherical to flat, and then further central part of the concave, highly evolved type of receptacle for the central concave bottle-like structure. There are several main types of receptacle (Fig. 39-1), which are compared with typical plant receptacle shapes. 1. Columnar receptacle The columnar receptacle has been seen in the magnolia of Experiment XXXVII. The receptacle of buttercup is shorter and hemispherical. They are all of a more primitive type. 2. Flat or slightly convex receptacle most angiosperms, such as Solanaceae, Leguminosae, Cruciferae and other plants of the receptacle has been further shortened, and slightly enlarged into a flattened disk, the parts of the flower in a whorled manner arranged on the receptacle. 3. The cup-shaped receptacle of peach blossom or peach blossom observed in Experiment 38 is a typical cup-shaped receptacle, with the center of the receptacle being concave. 4. vase-shaped receptacle pear subfamily, Asteraceae and cucurbitaceae female flowers with vase-shaped receptacle, that is, the receptacle is further sunken into a bottle, the ovary buried in it. (Calyx is a general term for sepals, the outer whorl of the perianth. The sepals are usually green and leaf-like, with internal anatomical structures similar to those of leaves, including epidermal cells, a large number of thin-walled cells containing chloroplasts, and vascular bundles. During the bud stage, the calyx acts as a protector of all other parts of the flower. Generally after flowering, the sepals are shed; some plants can retain the calyx until fruit maturity, known as the persistent calyx, such as eggplant, tomato, persimmon and other sepals. The persistent calyx has the function of protecting the young fruits. Morphological variation in the calyx can be roughly characterized by the following (Figure 39-2): 1. The sepals of the free calyx are separated from each other, such as the calyxes of buttercups, peaches, and other plants observed in Experiment XXXVII. 2. The sepals of the confluent calyx are united with each other, and the degree of union may vary. The lower part of the united calyx is called the calyx tube, and the upper part is called the calyx teeth or calyx lobes, such as the calyx of peas in experiment 38. In some plants the part of the calyx tube of the connate calyx elongates into a slender hollow tube called the spur. Observing the calyx of Impatiens balsa-mina or Consolida ajacis, the calyx tube is seen to elongate into a spur. 3. The calyx is petal-like mostly in single perianth flowers, lacking a corolla, the sepals are large and of a certain color, similar to petals, such as the calyx of hydrangeas in Experiment XXXVIII. 4. Calyx into a crown hairy or barb-like observation of dandelion fruit, the upper end of the crown hairs are developed by the sepals with the maturation of the fruit, can carry the seeds flying with the wind. The sepals of Bidens bipinnata are barbed and can be attached to the body of an animal to spread the seeds. 5. Epicalyx The epicalyx actually consists of the bracts of the flower. The outermost layer of the cotton flower in experiment XXXVIII has an epicalyx consisting of three large bracts. The epicalyx also has a protective effect on the buds and young fruits. (iii) Corolla types The corolla is a general term for the petals of the flower and is an inner whorl of the perianth. The corolla often comes in a variety of bright colors and is the most noticeable part of the flower. According to whether the petals are united, the flower will be distinguished into two categories of free flowers and petal flowers. Separate petals are separated from each other; the petals of the flower are united with each other, and the degree of union varies, partially united or fully united. The morphology of the corolla varies greatly, forming a variety of corolla types. Corolla type is one of the important basis for plant classification. Generally, plants of the same family often have the same type of corolla. The name of some plant families is named after the type of corolla, such as Cruciferae, Labiatae and so on. The common types of corolla are introduced as follows, requiring the combination of observation of typical plant flowers and wall charts, to understand the main types of corolla morphology and structural features: 1. Cruciform corolla radish, cabbage, February orchids and other cruciferous plants have a typical cruciform corolla flowers. It is characterized by four petals, free, the lower part of each petal is elongated into a claw, and the four petals are arranged in a cross shape (Figure 39-3, A). 2. Butterfly-shaped corolla Butterfly-shaped corolla is most common in legumes. Peas, soybeans, licorice (Glycyrrhiza uralensis), wisteria (Wisteria sinensis), acacia (Sophora japonica) and other plants have butterfly-shaped corolla. The corolla has five separate petals, each petal has a different form, such as the pea flower seen in experiment 38, its outermost piece of large petals known as the flag petal, flanked by a pair of winged petals, the middle two pieces of a slightly joint, into a keel-like protuberance, known as the keel petal. Five petals cooperate with each other, forming a beautiful butterfly-shaped corolla (Figure 39-3, B). 3. lip-shaped corolla medicinal plants motherwort (Leonurus artemisia), mint (Mentha haplocalyx), and flower beds in the common bunch of red (Salviasplendens) and other plants with lip-shaped corolla. The corolla consists of five petals united. Corolla base united into a tube, the upper part of the separation into two untidy lobes, shaped like the upper and lower lips, respectively, known as the upper lip and lower lip. General upper lip bifid, lower lip trilobed, sometimes the upper and lower lip cleft is not obvious. This type of corolla is the labiate corolla (Figure 39-3, C). 4. funnel-shaped corolla in the garden on the fence and roadside common with winding stems, white, pink or blue-purple flowers of petunias (Pharbitis bederacea), playing bowl flower (Calystegia hederacea) and other plants with a funnel-shaped corolla of flowers. Petals are generally five, all united into a long corolla tube, the corolla tube from the base upward gradually expanded into a funnel-shaped (Figure 39-3, E). 5. Bell-shaped corolla bell-shaped corolla and funnel-shaped corolla is similar, the petals are generally five, united into a corolla tube. However, the corolla tube of the bell-shaped corolla is shorter and thicker, slightly enlarged in the upper part, and bell-shaped. Platycodon grandiflorus, Adenophora stricta, and Platycodon grandiflorus have bell-shaped corollas (Figure 39-3, F). 6. Tall saucer-shaped corolla tall saucer-shaped corolla also by five petals united and become, the lower part of the corolla united into a thin tube, the upper part of the sudden horizontal unfolding, shaped like a tall saucer. Smell elegant daffodil (Narcissus tazetta var. chinensis) flowers and have a winding stem with beautiful small red flowers of grossularia (Quamoclit pennata) and other plants of the corolla is a tall saucer-shaped corolla (Figure 39-3, D). 7. Tubular corolla petals are five in number, connate into a tube, and have no apparent enlargement in the upper part. The central portion of the heads of Asteraceae sunflowers and chrysanthemums is tubular, and the heads of artichokes (Cephalanoplos segetum) are entirely bearing tubular flowers (Fig. 39-3, H). 8. ligulate flowers with five-numbered, connate petals. Corolla only the basal part of a few united into a tube, a little upward by the side of the united into a flattened ligule, ligule tip for teeth. Such as dandelion in the Asteraceae, endive (Ixeris chinensis) and so on in the head of the inflorescence is all ligulate flowers. The marginal flowers of sunflower heads are also ligulate (Fig. 39-3, G). 9. Solanaceae such as eggplant and wolfberry have a rotate corolla. Five petals only the base of the joint, forming a short thick corolla tube, the upper part of the petals are still separated, the lobes from the lower part of the middle to the surrounding radial expansion, so that the corolla is wheel-shaped, known as the spoke corolla (Figure 39-3, I). III. Morphological variation of stamens and pistils This experiment combines observations of objects, wall charts and models to introduce the morphological variation of stamens and pistils. (A) the morphology of the stamen variation 1. Stamen type generally more than one stamen in each flower, always called the stamen group. Most plants in the flower of the individual stamens are separated from each other, filament length is roughly equal. However, some plants have different types of stamens due to different filament lengths, filaments, anthers, the union or separation of different situations, the formation of different types of stamens, the main ones are as follows: (1) two-strong stamens There are four stamens in a flower, two of which have longer filaments, and the other two have shorter filaments (Figure 40-l, A). Observe the stamens of plants in the Labiatae family, such as motherwort and solstice grass (Lagopsis supina). (2) Four Strong Stamens A flower with six free stamens, four of which have longer filaments and the other two have shorter filaments (Fig. 40-1, B). Observe the stamens of cruciferous plants such as cabbage, radish, and February orchid. (3) Single Stamens The stamens are numerous and their filaments are partially united, while the anthers remain individually separated (Fig. 40-1, C). Stamens have been observed in cotton in Experiment XXXVIII, and in other plants of the mallow family such as fuchsias and marshmallows (Althaea rosea). (4) Aggregate Stamens Stamens are numerous, with filaments separated individually and anthers united with each other to form aggregate stamens (Fig. 40-1, F). Observe the stamens of plants in the Asteraceae family, such as sunflowers and dandelions. (5) two-body stamens such as experiment thirty-eight has observed the stamens of pea flowers that is two-body stamens. Of the ten stamens, nine stamens filaments are united with each other and anthers are separated, and the other stamen is solitary (Figure 40-1, D). Most legumes have two stamens. (6) Polygamous stamens The number of stamens for the majority, divided into several groups, each group of stamens, filaments partially united, the upper filaments and anthers remain separate, the formation of polygamous stamens (Figure 40-1, E). Such as the stamens of Hypericum monogynum. 2. Anther dehiscence When the pollen matures, the anthers dehiscentiate in different ways, dispersing the pollen. The most common way of anther dehiscence is longitudinal dehiscence, i.e. the anther dehiscence along the longitudinal axis of the anther chamber. Examples are the forms of anther dehiscence in wheat, corn, and lily anthers (Fig. 40-2, A). Pore cleavage is the cleavage of a small hole at or near the top of the anther, through which pollen is dispersed, as in the form of anther cleavage in potato and eggplant of the Solanaceae family (Fig. 40-2, B). Another, less common form of valvular dehiscence is the formation of 1-4 valve-like segments on the anther chamber at maturity, from which pollen is dispersed when the segments are lifted upward. Such as the form of anther dehiscence in Camphoraceae and Berberidaceae (Figure 40-2, C). (ii) Pistil type and placenta type The pistil consists of three parts: the stigma, the style, and the ovary, and is generally vase-shaped. The pistil is surrounded by a metamorphosed leaf-carpel. The midrib in the carpels, which corresponds to the midrib of the leaf blade, is called the dorsal suture, and the places where the carpels join or merge with each other are called the ventral suture. Generally the ovules are inserted on the ventral suture. Where the ovule is inserted in the ovary is called the placenta. A pistil may consist of a single carpel or multiple carpels. Due to the different number of carpels constituting the pistil, as well as the different ways in which the carpels are united, a variety of types of pistils are formed, and accordingly different types of placentas have emerged. 1. The monopistil is composed of a single carpel united to form an ovary chamber, with the ovules inserted on the ventral suture line as a marginal placentation (Fig. 40-3, E, F). Observe the pistil of a legume, which is surrounded by a single carpel. A longitudinal and transverse section of the ovary reveals that several ovules are borne on one side of the elongated ovary (at the ventral suture line where the carpels come together) in only one locule. After fertilization, the ovary develops into a pod. 2. The unicompartmental compound pistil consists of several carpels (usually 3-5 carpels) united at the ventral suture line, *** with the same surrounded by an ovary chamber, the ovules are borne on each ventral suture line, forming a lateral membranous placentation (Fig. 40-3, A, B). Observation of the pistil of the violet-flowered groundnut (Violayedoensis) or poppy (Papaver somniferum). The pistil of Violayedoensis is a unicellular compound pistil united by three carpels. Each ventral suture bears two rows of ovules, which develop into a capsule after fertilization. When the capsule along the dorsal suture line after dehiscence, can obviously see each abdominal suture line bearing two rows of tiny seeds. In the unicellular compound pistil, there can be another type of placentation, which is at the base of the cavity of the ovary grows upward a column, this column does not reach the top of the ovary, the ovules are inserted on the column, called the central placentation. This type of placentation can be seen when observing the ovary of Dianthus or Amaranthus. 3. Multilocular compound pistil pistil consists of multiple carpels (usually also 3-5 carpels) united. The carpels are united at the ventral suture line and extend inward to form a septum, which converges at the center of the ovary to form a central axis. The cavity of the ovary is separated by the septum into several locules (e.g., three locules in three carpels; five locules in five carpels). The ovule is inserted on the mesocarp and is the mesocarpal placenta (Fig. 40-3, C, D). Looking at the pistil of cotton, petunia, and other plants, the septum in the ovary and the ovules borne on the median placenta can be seen by transverse and longitudinal cuts. 4. Polycarpous free gynoecium There are several monopistils in a flower, each surrounded by a single carpel. Such as experiment 37 observed in the magnolia and buttercup flower pistil type, are multi-carpel free gynoecium. (C) Ovary in the receptacle bearing position and the position of the corolla changes Due to changes in the shape of the receptacle, the corresponding position of the ovary in the receptacle bearing position and the position of the corolla bearing changes, the formation of the superior ovary, inferior ovary and semi-inferior ovary, as well as the corresponding inferior, superior and circumferential flowers. 1. Superior ovary and inferior flowers when the receptacle is flat or slightly convex, the ovary is inserted only at the base on the receptacle, and the other parts are not fused with the receptacle, which is the superior ovary. As previously observed, legumes, lycophytes, and crucifers, etc., are mostly epigynous. In this case, the calyx and corolla are inserted on the outer edge of the receptacle, and their position with respect to the ovary is that of an inferior flower (Fig. 40-4, A). Peach blossoms with a cup-shaped receptacle, but with an ovary that is not fused to the receptacle except at the base, are still epigynous, while the position of the corolla insertion relative to the ovary is perigynous (Fig. 40-4, B). 2. Inferior ovary and superior flower The receptacle is sunken into a vase shape and encloses the ovary, and the entire ovary is fused to the receptacle, constituting the inferior ovary. Observe the pear (Pyrus) flowers, sunflower tubular flowers or cucumber female flowers, are inferior ovary. The calyx and corolla are inserted on the edge of the upper opening of the vase-like receptacle, and their position relative to the ovary is that of an epigynous flower (Fig. 40-4, D). 3. Semi-inferior ovary and perigynia Observe a specimen of Codonopsis pilosu-la with a cup-shaped receptacle, the lower half of the ovary buried in the receptacle, constituting a semi-inferior ovary, and its corolla positioned relative to the ovary as a perigynia (Fig. 40-4, C). Types of Inflorescences The flowers of some plants are each borne singly on a stem and are solitary. Many plants have a number of flowers that are borne in a certain order and form on the same inflorescence axis as the ****, forming an inflorescence. There are no typical nutritive leaves on the inflorescence, and only a simple bract is borne under each flower, or an involucre is borne under the whole inflorescence. This experiment combines observations of the major inflorescence types with objects and wall charts. Inflorescences can be divided into two main categories, finite and infinite, based on the order in which the flowers open on the inflorescence axis. In limited inflorescences, the flowers at the top or center of the inflorescence axis open first, then sequentially downward or outward one by one, and the tip of the inflorescence axis does not continue to elongate. These inflorescences are rare. Most inflorescences bloom from the bottom up or from the outside to the inside, during flowering the inflorescence axis can continue to elongate and differentiate new flower buds, so it is called infinite inflorescences. (A) the main types of infinite inflorescences in infinite inflorescences, due to the presence or absence of each flower or the length of the stalk of the flower, as well as the length of the inflorescence axis and whether there are branches and other different situations, the formation of nine main types of inflorescences. 1. Racemes Racemes have an elongated unbranched inflorescence axis on which are borne a number of flowers with stalks of basically equal length. The anterior end of the inflorescence axis may continue to elongate and differentiate into new flower buds. The flowering sequence is a gradual opening of flowers from the bottom up (Fig. 41-1, C). Observe the inflorescences of caper and wisteria. In the caper inflorescence, it can be seen that the lower part of the inflorescence has formed a short hornbeam, while the apical flowers are in bud or opening. 2. The basic characteristic of the spike is the bearing of numerous sessile florets on an unbranched inflorescence axis (Fig. 41-l, B). In experiment XXXVIII, the gramineous wheat has a compound spikelike inflorescence. Others, such as plantain, have typical spikes. 3. Catkins have unbranched inflorescence axes and sessile flowers that resemble spikes. It is characterized by each inflorescence consisting of unisexual flowers (male or female), the inflorescence axis is soft and pendulous, and the entire inflorescence falls off after flowering or fruit ripening (Figure 41-1, G). The poplar and willow genera seen in Experiment XXXVIII both have catkins. 4. Fleshy spikes are also similar in basic structure to spikes, but their inflorescence rachis is plump and fleshy. Such as the female inflorescence of corn. Some flesh spike inflorescence is covered with a large bracts, shaped like a corolla, specially called spathe, such as calla lily (Zantedeschia aethi-oPica). This inflorescence is sometimes called a spathe. 5. Umbel is characterized by the shortening of the inflorescence axis into a sphere, on which most flowers with stalks of nearly equal length are concentrated. The entire inflorescence has the appearance of an open umbrella, so it is called an umbel (Figure 41-1, E). The order of flowering is from the outside in. Plants such as edible shallots and leeks (Allium tuberosum) have umbels. The inflorescences of carrots are compound umbels. 6. Corymb inflorescence inflorescence axis is not branched, slightly elongated, which bears a number of flowers with unequal petioles, by the lower flowers of the longer flower stalks, the higher the shorter flower stalks, so that the entire inflorescence of the flowers in the upper arrangement of a flat surface (Figure 41-1, D) Observe the inflorescences of the trilobate hydrangea (Spiraea trilobata), pear, apple and other plants. 7. Cephalic inflorescences are generally considered to be the more evolved type of inflorescence, and most plants in the Asteraceae family have cephalic inflorescences. The "single" chrysanthemum that you see every day is actually an inflorescence consisting of many sessile flowers densely attached to a shortened capitate or discoidal inflorescence axis with an involucre below the inflorescence axis (Fig. 41-l, F). The order of opening of the individual flowers in a capitate inflorescence is gradual from outside to inside. Observe the inflorescences of plants such as sunflowers and dandelions. 8. Cephalic inflorescences These inflorescences are more specialized and are not often seen. They are characterized by a shortened and inflated fleshy inflorescence axis with a sunken central part. Flowers are attached to the sunken part of the inflorescence axis, and are surrounded by the expanded fleshy inflorescence axis, leaving only an opening at the tip, and the flowers are not visible on the outside, so they are called cryptomeria. It is sometimes mistaken for a non-flowering but fruit-bearing plant, as in the case of the fig (Ficus carica), for which it is named. Others, such as Ficus microcarpa, also have cryptomeres. 9. Panicle is actually a compound inflorescence. It is characterized by a branched inflorescence axis. Each branch can be a raceme or spike, etc., and the entire inflorescence is conical in shape, always referred to as a panicle (Figure 41-1, A). Observe the inflorescences of plants such as pearlberry (Sorbariakirilowii), lilac, and rice, all of which are panicles. (ii) Limited Inflorescence Types Limited inflorescences have inflorescence axes that no longer elongate apically, and new flower buds occur on the lateral axes. Due to the number of lateral axes and the different forms of growth of the lateral axes, the following types are formed: 1. After the opening of the terminal flower of the inflorescence axis of a monochasial cyme, only one lateral bud opens under it, and grows into a lateral axis. On the lateral axis, the terminal flower opens first, and another lateral bud opens beneath it, and so on to form a monochasial cyme (Fig. 41-2, A). If the lateral branches occur at intervals from left to right, a scorpion-tailed cyme is formed, which can be observed in the opening of the inflorescence of iris and calamus (Gladiolus gandavensis); if the lateral branches all occur in the same direction, a spiral cyme is formed, which can be observed in the opening of the inflorescence of hem erocallis (Hem erocalliscitrina) and daylilies (Hem eroc allis fullva) can be observed in the opening of the inflorescences. 2. After the terminal flower of the inflorescence axis opens, a pair of lateral buds underneath opens at the same time and grows into a lateral branch, and after the terminal flower of the lateral branch opens, it grows branches in the same way, thus forming a dichasial cyme (Figure 41-2, B). Observe the inflorescences of plants such as Euonymusbungeanus and Dianthus chinensis. 3. After the flowers at the tip of the main axis of a dichasial cyme open, several lateral branches occur simultaneously below. The length of the lateral branches exceeds that of the main axis. After the opening of the flowers at the top of each lateral pole, several lateral branches occur in the same way. This type of inflorescence is a dichasial cyme. Such as the inflorescence of EuPhorbia pekinensis. 4. Verticillaster is composed of cymes with shortened inflorescence axes inserted in the axils of opposite leaves. From the outside, they look like flowers arranged in whorls on the stem, hence the name Verticillaster (Figure 41-2, C). Observe the inflorescences of plants such as motherwort, solstice grass, and mint in the family Labiatae as whorls.