In this article we will discuss about:- 1. General Features of the Cyperaceae 2. Floral Range in the Cyperaceae 3. Divisions 4. Position and Affinity 5. Number and Distribution 6. Commonly Occurring Plants 7. Economic Aspects.
General Features of the Cyperaceae:
Habit – Annual or perennial grass-like herbs with a sympodial rhizome and a solid triangular culm.
Leaves – Linear, tristichous without a ligule; leaf-sheath closed.
Inflorescence – Spike or head of spikelets or panicle.
Flowers – Bisexual or unisexual, small, subtended by imbricating bracts.
Perianth – Absent or represented by 3 or 6 scales or bristles.
Androecium – Stamens 3, in 1 whorl; anthers basifixed.
Gynoecium – Carpels 3, united; ovary superior, unilocular; ovules single, erect, anatropous; stigma tripartite, papillose.
Fruit – Achene or nut.
Seeds – Albuminous; cotyledon comes out of sheath during germination; embryo embedded in endosperm.
Floral Range in the Cyperaceae:
The spikelets are 1-flowered in Diplacrum or many-flowered in Schoenus.
In general, the flowers are bisexual. But unisexual flowers exist in Carex. In Elyna, the secondary axis bears male flowers above the females. The secondary axis may be elongated and forms a bristle like projection, as in Uncinia.
The flowers are naked or the perianth is reduced to bristles in Scirpus or hairs in Eriophorum. Oreobolus has 6 perianth segments arranged in two whorls of 3 each. In Rhynchospora and other genera, the perianth segments are numerous.
The androecium generally contains 6 stamens, but sometimes 3 stamens are present. A single stamen is found in Bisboeckelera and Hemicarpha.
The gynoecium consists of 2 or 3 carpels, being noted in the species of Carex.
Divisions of the Cyperaceae:
The Cyperaceae is divided into three subfamilies:
Subfamily I. Caricoideae:
Spikes many-flowered. Flowers unisexual, naked. Carpels borne in a sac-like structure called perigynium. Examples- Carex, Kobresia, etc.
Subfamily II. Rhynchosporoideae:
Spikelets 1- to few-flowered, cymosely arranged. Flowers bisexual or unisexual. Examples- Bisboeckelera, Rhynchospora, etc.
Subfamily III. Scirpoideae:
Spikelets many-flowered. Flowers bisexual. Examples- Cyperus, Scirpus, etc.
Position and Affinity of the Cyperaceae:
Bentham-Hooker placed the Cyperaceae (along with the Gramineae) in their seventh and last series of monocots, the Glumaceae, on account of flowers being subtended by glumaceous bracts. Using the same basis, Engler included the family in the Glumiflorae which also contained the Gramineae.
Hutchinson segregated the families into two distinct orders, the Cyperales and Graminales of the division Glumiflorae and interpreted them as being “derived from liliaceous ancestors via the Juncaceae complex”. Hutchinson’s circumscription of the two orders was followed by Stebbins as well as Dahlgren and Clifford.
Takhtajan and Dahlgren treated the family under the last order Poales of the Commelinidae and Commelinanae respectively. But Cronquist considered the cyperaceae and Gramineae under the Cyperales lying between the Juncales and Typhales.
According to Thorne, the two families are components of the Commelinales which in turn was put in the Commeliniflorae. Ehrendorfer created the Juncanae in order to accommodate the Cyperales and the Commelinanae for the Poales.
The Cyperaceae resembles the Gramineae in so far as the habit is concerned. But the features of flower, fruit and seed as well as the method of germination sharply delimit the two families. That is why there is a growing tendency not to regard the Gramineae as a close ally of the Cyperaceae.
Recent studies have indicated that phylogenetic significance should not be attached to the superficial grass-like habit, since it has made its appearance in families which are not related to the Cyperaceae and Gramineae.
The spikelets of the Cyperaceae are not at all homologous with those of the Gramineae, as they vary widely in arrangement in the former and have remained reasonably constant in the latter. The florets of the Cyperaceae are axillary in position, while in the Gramineae (excluding the bracts) they are borne terminally.
A definite perianth can be somewhat demonstrated in the Cyperaceae, but the fruits with two or three carpels are less specialised than the caryopsis of the Gramineae. The basic placental condition of the Cyperaceae is a derivative of the ancestral free-central type, whereas it has arisen from a parietal type in the Gramineae.
The ovules are chiefly anatropous in the Cyperaceae and chiefly orthotropous in the Gramineae. The embryo of the Cyperaceae is embedded at the base of the endosperm and not outside of it, as in the Gramineae. In the Cyperaceae, the terminal portion of the cotyledon comes out of the seed and the other portion remains in the seed to function as a sucker; in the Gramineae, neither the cotyledon nor any part comes out of the seed.
In view of the above considerations, it has been thought that the two families belong to two separate orders and that they do not indicate bond of phyletic relationship. However, Cronquist (1968) believed that “it is most useful to group the Gramineae and Cyperaceae in a single order Cyperales”.
It is quite possible, according to Blaser (1940), that the Cyperaceae arose from “small- flowered, few-seeded, hypogynous Liliales with axile placentation … the transition having occurred through loss of septa and placental axis and may have occurred through some line not now recognisable”.
Number and Distribution of the Cyperaceae:
The Cyperaceae is a very large family which is made up of approximately 90 genera and 4,000 species. The members of this family are chiefly subarctic and temperate in distribution, although some are found in the tropics. They are seen in relatively wet situations, such as marshes, bogs and swamps.
Commonly Occurring Plants of the Cyperaceae:
Bulbostylis barbata (Rottb.) Clarke is an annual herb.
Slough Grass (Carex indica L.) is seen in sandy areas.
Cyperus brevifolius (Rottb.) Hassk. is a weed, bearing white globose heads.
Sedge (Cyperus rotundus L.) is a weed of cultivated lands.
Fimbristylis complanata Link, is a weed, having a glabrous stem flattened under the umbel.
Fimbristylis junciformis Kunth. inhibits wet places.
Scirpus articulatus L. is a glabrous herb with flowering glumes spirally arranged.
Economic Aspects of the Cyperaceae:
Economically, the Cyperaceae is of considerable importance. Carex atheroides (USA) is utilised as a haygrass. The leaves and stems of C. brizoides (Central Europe) are used as a packing material. The leaves of C. dispalatha (Japan) are used to make hats. C. paniculata and C. riparia are employed in stables instead of straw.
The stems of Cladium effusum (tropical America) constitute a source of cheap paper. C. mariscus (North Africa) are used for thatching houses. The stems of Cyperus articulatus and C. longus bear sweet-scented rhizomes and roots which can be used in perfumery. The tubers of C. esculentus (Europe), Eleocharis aulcis, E. tuberosa (Japan) and Scirpus grossus are edible.
The pith of Papyrus Plant (Cyperus papyrus) is the classical material used by the Egyptians for making paper. The split stems of C. malacopsis, C. tegetifornis, Lepironia articulata and Juncellus inundatus are woven into mats.
C. rotundus is a remedy for dysentery, whereas Mariscus sieberianus (Sumatra) is used as a vermifuge and Scirpus articulatus as a purgative. The stems of Eleocharis austro-caledonica are used for basket work, those of Lepironia muoronata for packing, Scirpus lacustris for chairseats and S. totara for canoes and rafts.
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