Botany - B.E. Yakubenko 2017

Part Three. The Plant Kingdom (Plantae)
Chapter IX. Division Angiosperms, or Flowering Plants (Angiospermae, Magnoliophyta)
Laboratory Session Topic 14.37. Flower Morphology

General Remarks. The flower is one of the most essential diagnostic features of angiosperms. Due to this characteristic, they are referred to as flowering plants. A flower is a generative organ. It evolved as a metamorphosed, shortened, and unbranched SHOOT adapted for The formation of micro- and megaspores, Gametes, cross-Pollination and Fertilization, as well as The production of fruits and seeds. The most critical part of the flower is the pistil, specifically the Ovary, which gives rise to ovules that subsequently develop into seeds.

Objects:

1. Flower of sour cherry (Cerasus vulgaris L.)

2. Flower of garden pea (Pisum sativum L.)

3. Flower of common sage (Salvia officinalis L.)

4. Flower of cereal rye (Secale cereale L.)

Tasks:

1. Examine the general Structure OF THE actinomorphic cherry flower.

2. Examine the Structural Features of the papilionaceous pea flower.

3. Examine The structure of the zygomorphic bilabiate sage flower.

4. Examine the structure of the rye spikelet and flower.

5. Draw the structure of the studied objects and label their component parts.

Equipment and Materials: MBR-1 or Biolam microscopes, magnifiers, scalpels, forceps, living and fixed materials, and other accessories.

Macroscopic Study of Various Flower Types. To perform this exercise, take living and fixed flowers in the following order: cherry, pea, sage, and rye spikelets, and arrange the floral parts on a Glass slide so that all their components can be examined.

To do this, use a dissecting needle to separate the pedicel, calyx, receptacle, petals, stamens, and pistil. In the cherry flower, the sepals, petals, and stamens are attached to the rim of a cup-shaped receptacle known as the hypanthium. Another characteristic feature of the flower is that the pistil is free, forming a superior ovary. It is easy to determine that the cherry flower is actinomorphic, possesses a double perianth (five free sepals and five free petals), numerous stamens, and a single pistil. Upon tearing the hypanthium, one can observe that the pistil consists of an expanded ovary, a style, and an undivided capitate stigma, indicating that it is formed by a single carpel. Draw the cherry flower in vertical section and label its parts. Separately, draw the stamen and the pistil, and label their parts.

On a glass slide, arrange the garden pea flower in the same manner by detaching all of its parts. It is evident that the flower is zygomorphic, featuring a fused-sepals calyx and a papilionaceous corolla. The latter comprises a large standard (banner) petal, two smaller lateral wings, and two partially fused keel petals. After using a needle to separate the inner floral parts—the androecium and gynoecium—you will see that nine stamens are fused by their filaments, and their number can only be counted by their free anthers. The fused stamens enclose the pistil in a tube, while one stamen remains free. Tearing the staminal tube will release the pistil for structural examination. It can be seen to possess an elongated cylindrical ovary and a curved short style with an undivided stigma. Draw the dissected pea flower, along with the androecium and pistil separately, and label all their parts.

Place the sage flower on a glass slide, paying attention to its bilabiate corolla. Using a needle, separate the calyx and the corolla. It will become apparent that the calyx has five uneven Teeth with fused sepals. The corolla features an upper lip formed by two petals and a lower lip formed by three petals. By tearing the corolla tube, detach the stamens attached to it. There are four stamens, two of which are shorter. Between them, you will notice the pistil style with a forked stigma, while the ovary of the pistil will be found at the Base of the calyx. Note that the ovary is not undivided, but four-lobed. Draw the sage flower and label all its component parts.

Examine the structure of the grass flower and spikelet using living plants or fixed material, having previously studied their structure from a chart. Next, detach an elementary spikelet from the compound spike and place it on a glass slide. Using a needle, remove the two rough scales from the base of the spikelet—the upper and lower glumes. Inside, between the glumes, There are two well-developed flowers and one underdeveloped one. Separate one developed flower and arrange its parts on a glass slide: the lemma (which is membranous) and the palea (which is coarser and bears an awn). Between the floral scales lie two tiny lodicules, three stamens, and one pistil with a two-lobed feathery stigma. The ovary is superior. Draw a diagram of the structure of the elementary spikelet and flower, and label the glumes, lemmas/palea, lodicules, stamens, and pistil (see Fig. 117).

In addition to drawings, the structure of a flower can be represented by a formula. A formula is a concise and fairly comprehensive way of describing a flower using conventional symbols. The following conventional symbols are used in floral formulas: P (perigonium) — simple perianth; Ca, K (calyx) — calyx; Co, C (corolla) — corolla; A (androecium) — stamens; G (gynoecium) — pistil. Numbers following these symbols indicate the number of floral parts; if they are fused, the numbers are enclosed in parentheses. An actinomorphic flower is designated by an asterisk, and a zygomorphic flower by an arrow. A line placed below or above the pistil symbol denotes a superior or inferior ovary, respectively. For example, the floral formula of the cherry is written as follows: *K₅C₅A∞G₁, and that of the pea as ↑K₍₅₎C₁+₂+₍₂₎A₍₉₎+₁G₁.

Conclusion. The primary diagnostic feature of the angiosperm division is the presence of a flower. A flower is a shortened, modified shoot that facilitates the processes of sporogenesis, pollination, Development of the female and male gametophytes, fertilization, and the Formation of the Seed and Fruit. Morphologically, the flower is homologous to the strobili of higher spore-bearing plants, but its Functions are far more complex than those of strobili, where only spores are produced.

The adaptive features and biology of the flower are closely linked to pollination conditions, particularly entomophily (insect pollination), which is characteristic of most plants. The flower exhibits a diverse morphological structure that has developed through evolution and serves an adaptive function.

Class="center">Self-Control Questions

1. What are the calyx and corolla of a flower called when taken together?

2. What is the collective term for the stamens of a flower?

3. WHAT IS A flower with radial Symmetry called?

4. What are flowers without a perianth called? Give Examples.

5. Name the constituent parts that form the corolla of a pea flower.

6. Name the PARTS OF THE pistil. What is their origin?

7. What is a gynaecium consisting of fused carpels called?

8. What is a flower called through which theoretically only one plane of symmetry can be drawn?

9. What represents the male gametophyte in angiosperms? 10. What represents the female gametophyte in angiosperms?