504 



BOTANY OF THE LIVING PLANT 



tTC 



paleae : the lower and outer is anterior, the upper and inner is posterior, and 

 the flower itself lies between them. At flowering they gape widely apart, so 

 as to expose the parts of the flower. If a flower be found in this condition, 

 or if the lower palea be forced back, the flower, as seen from the anterior 

 side, wdll show the following parts : 



(i) Two lodicules, which are minute, colourless, hypogynous scales, right 

 and left of the median plane. It is by their swelling that the paleae are 

 forced apart at the time of flowering. 



(ii) Three stamens, hypogynous, free, with long flexible filaments, and 



versatile anthers, bearing powdery 

 pollen. One stamen is median 

 and anterior, the two others 

 obliquely posterior. 



(iii) Certainly the gynoecium 

 consists of a pear-shaped superior 

 ovary, grooved on the posterior 

 side, and bears distally, right and 

 left, two feather}^ stigmas. Dis- 

 section shows a single ovule in 

 the ovary. 



The number of such flowers in 

 each spikelet varies : 8 to lo are 

 common numbers, and they open 

 at intervals in acropetal succes- 

 sion. 



The flower may be held to be of 

 Liliifloral type, reduced in rela- 

 tion to wind-pollination. The 

 perianth is represented by the 

 two lodicules, corresponding to 

 the oblique anterior segments of 

 the inner series, which being of 

 use in separating the paleae at 

 flowering have survived. The 

 stamens correspond in position to 

 the outer whorl of the Liliiflorae, 

 while the gynoecium is held to consist of a single carpel, corresponding to 

 the anterior carpel of the Liliiflorae. This floral structure is very constant 

 in the Grasses, but the flowers are variously disposed in their inflorescences. 

 The Rye-Grass may be taken as a good example for the Family, and it is 

 easily recognised. 



The inconspicuous flowers, versatile anthers, dry dusty poUen, and expanded 

 feathery stigmas clearly indicate wind-pollination. Most Grass-flowers are 

 homogamous, that is, stamens and stigmas mature simultaneously, but some 

 are protogynous {Alopecurus) . 



The fruit is a dry nut, containing one albuminous seed and a lateral embryo. 

 Its structure is well illustrated by the grain of wheat or maize (Fig. 407). 



Fig. 407. 



Part of a median longitudinal section of a [grain of 

 Wheat, shomng embryo and scutellum (sc). vs =vasc. 

 bundle of scutellum; ce=its columnar epithelium; 

 r=ligule; c= sheathing part of cotyledon; ^y= vege- 

 tative cone of stem; /z^ = hypocotyl ; /=epiblast; 

 r= radicle; cZ = root sheath ; j>j = micropyle ; / = funi- 

 culus ; i;_^ = vascular bundle of funiculus; /=lateral 

 wall of groove; c^=pericarp. ( x 14.) (After Stras- 

 burger.) 



