Botany - B.Ye. Yakubenko 2017

Part Three. Kingdom Plantae
Chapter IX. Division Angiosperms, or Flowering Plants (Angiospermae, Magnoliophyta)
Laboratory Class Topic 14.51. Sedge Family (Cyperaceae)

General Remarks. The Cyperaceae family comprises perennial (rarely annual) herbaceous plants with long or short rhizomes. The stem is typically triquetrous, occasionally cylindrical, filled with parenchymal tissue internally, and lacks thickened nodes. Leaves are mostly arranged in three rows, linear, with closed sheaths and no ligule. Flowers are unisexual or bisexual, and plants are sometimes dioecious. Each flower sits in the axil of a bract scale. The perianth is reduced to bristles or scales, or is entirely absent. There are usually three stamens, rarely two; the pistil consists of 2–3 carpels with a superior Ovary containing a single anatropous ovule, a single style, and 2–3 filiform stigmas. In addition to the bract scale, the pistillate flower is protected by a perigynium formed by the fusion of two bract scales. The shape and size of the perigynium vary. The inflorescence in sedges is spicate, paniculate, or capitate, composed of single-flowered spikelets in the axils of leaf-like or scarious bracts. The fruit is a nutlet, either triquetrous or biconvex. The economic importance of the family is relatively low. Sedge hay is poor in protein and coarse (rich in silica); however, the thickened rhizomes of certain species (such as tiger nut) are rich in starch and oil, making them edible. In ancient times, papyrus (Cyperus papyrus) played a crucial role in paper production. In some regions, species of this family are used for sand stabilization, while others play a significant role in peat formation.

Like grasses (Poaceae), sedges are distributed globally. Superficially, they resemble grasses, but a closer examination reveals essential differences. For instance, the stem of grasses is a culm with well-developed nodes and internodes, mostly hollow inside. Their leaf sheaths are open, and a ligule is present between the sheath and the blade. The inflorescences and flowers are bisexual, and the fruit is a caryopsis. In contrast, sedges have a triquetrous, solid stem without nodes. Their leaf sheaths are closed, and the ligule is absent. The inflorescences and flowers are unisexual, and the fruit is a nutlet.

Objects:

1. Slender tufted sedge (Carex acuta L.)

2. Tussock cottongrass (Eriophorum vaginatum L.)

3. Slender clubrush (Scirpus sylvaticus L.)

4. Sea clubrush (Bolboschoenus maritimus (L.) Palla)

5. Lake bulrush (Schoenoplectus lacustris (L.) Palla)

Tasks:

1. Perform a morphological Analysis of the specified plants, identify their most characteristic features, and study the General characteristics of the family.

2. Using slender tufted sedge as an example, perform a morphological analysis and taxonomic identification.

3. Compare the morphological structures of vegetative and Generative Organs in Cyperaceae and Poaceae.

Macroscopic studies. Macroscopic studies are conducted using live or herbarium material of the slender tufted sedge (Carex acuta). The slender tufted sedge is a perennial herbaceous plant, green in color, featuring a long underground rhizome that often forms small turfs and hummocks. Thanks to its rhizome, the plant propagates mainly vegetatively. The stem is sharply triquetrous, surrounded by brown or dark brown leaf-bearing sheaths. The leaves are linear, parallel-veined, long, and 5–8 mm wide. Phyllotaxy is tristichous. The inflorescence is racemose. There are 5–10 unisexual spikelets. The pistillate spikelets are cylindrical, lax, 3–10 cm long, with the lower ones positioned on often long, drooping stalks. The lowest bract exceeds or equals the inflorescence. The lower spikelets are pistillate, while the upper ones are staminate. The covering scales are acute, blackish-brown, with a white center. Pistillate flowers bear obovate, biconvex, rusty-brown perigynia, 3 mm long. There are two stigmas. The fruit is a nutlet. It grows in marshy meadows, bogs, and along the banks of rivers and lakes.

Begin the plant identification by determining the family, and record the identification steps in your notebook.

Family identification path: 1, 9 —, 15, 16—, 42—, 47—, 48—, 49, 50—, 51—, 52—, 54, 55—, 57—. Cyperaceae, p. 111.

Genus identification path: 1, Sedge — Carex,

Species identification path: 1—, 6—, 26—, 27, 32, 33, 34—, 38, 39—, 40—, 41.

Slender tufted sedge — Carex acuta L.

Conclusion. Identifying sedges, especially initially, is quite challenging. It requires careful examination of the flowers, inflorescences, Structural Features of vegetative organs, their shapes and arrangements, as well as a thorough knowledge of fruit types.

Class="center">Self-Assessment Questions

1. What are the life forms found in Cyperaceae?

2. How does the stem of sedges differ from that of grasses?

3. What is the shape of the sedge leaf and how are the leaves arranged on the stem?

4. How does the leaf Structure of sedges differ from that of grasses?

5. What is The structure of pistillate and staminate flowers in sedges?

6. How do the flowers of sedges and grasses differ in their structure?

7. What types of spikelets can be found in the inflorescence of sedges?

8. What is the underground part of the plant called in most sedges?

9. What is the Practical significance of the family?