502 



BOTANY OF THE LIVING PLANT 



The chief genus is Juncus, to which the Rushes belong. They are mostly 

 plants of moist habit, and of little feeding value for stock. Their presence 

 in grass-land is an indication of the need for draining. 



Family : CYPERACEAE. Examples : COTTON-GRASS, SEDGE. 



(9) The Cotton-Grass (Eriophorum vaginatum, L.) is a tufted perennial 

 herb of swampy moorlands, marked by its single cottony heads when in fruit. 

 The flowering head rises about a foot from the root-stock, and is composed of 

 a single spikelet of flowers in the axijs of glume-like bracts. Each herma- 

 phrodite flower is constructed as follows : 



Perianth, inferior, represented by numerous bristles, which are developed 

 relatively late, and mature into the " cotton " of the fruit. 



Androecium, stamens three, hypogynous, representing those of the inner 

 whorl. 



Gynoecium, carpels three, syncarpous, and superior, with three stigmas. 

 The ovary is unilocular, with a solitary ovule (Fig. 404). 



Pollination is effected by the wind, which also carries out the transfer of the 

 fruit. 



Fruit, a trigonous nut, with the cottony tuft of the persistent 

 perianth attached at its base. The floral structure suggests a modification 



of the Liliaceous type, by cottony develop- 

 ment of the perianth, loss of the three 

 outer stamens, and reduction of the ovary 

 to a single loculus with one ovule. 



(10) For the structure of a Sedge, any of 

 the following species of Carex will serve 

 (C. glauca, Murr; pallescens, L. ; pendula, 

 Huds. ; hirta, L. ; flava, L. ; or binervis, 

 Sm.). The Sedges are perennial herbs 

 of swampy ground, which put up long 

 flowering shafts, each bearing several spikes 

 of unisexual flowers (Fig. 405). In the 

 species named, one or more of the distal 

 spikes bears only male flowers : the lower 

 lateral spikes bear female flowers. In the 

 axil of each glume-like bract of the male 

 spike is a male flower consisting only of 

 three stamens, with no perianth or gynoe- 

 cium. In a similar position on the female 

 spikes there are found flask-shaped bodies 

 (perigynid), through the open throat of 

 which at flowering a three-branched stigma 

 projects. The perigynium is a bract enveloping the female flower, which has 

 no perianth, and no androecium, but consists of three, or sometimes two 

 carpels, syncarpous and superior. The ovary is unilocular, the ovule 

 solitary, and fruit a nut. Here the flower is still more simple than in the 

 Cotton-Grass, for there is no perianth, and as the flowers are unisexual, all 

 that remains are the three stamens in the male, and the three carpels in the 



FIG. 405. 



A, floral diagram of a male flower of 

 Carex ; B, of a female flower with three 

 stigmas ; C, of a female flower with two 

 stigmas. D, diagram of female flower of 

 Carex. E, diagram of the hermaphrodite 

 spikelet of Elyna : a, secondary axis ; utr. 

 utricle or bract of secondary axis. (After 

 Eichler.) (Strasburger.) 



