732 



BOTANY 



PART II 



Family 2. Gramineae ( 42 ). The stems of the true Grasses are 

 cylindrical, and have hollow internodes (exceptions Maize and Sugar- 

 cane) ; the nodes are swollen ; the leaves are two- ranked and their 

 sheath is usually split and thickened at the node. At the junction of 

 the sheath and leaf-blade a membranous structure (the ligule) projects 

 (cf. Fig. 133). The flowers of the Gramineae are grouped in spicate, 

 racemose, or paniculate inflorescences, which are always composed 

 of partial inflorescences, the spikelets. Usually each SPIKKLET bears 

 several flowers. At the base of the spikelet there are usually (Fig. 

 811) a pair of sterile bracts (GLUMAE) ; sometimes there is only one 

 or 3-4 glumes. Continuing the two -ranked arrangement of the 



tr. O 



V 



FIG. 810. 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, 

 utriculus or bract of the secondary axis. 

 (After BICHLER.) 



FJG. 811. Diagrammatic 

 representation of a Grass 

 spikelet. g, The glumes ; 

 Pi and p->, the inferior 

 and superior palea ; e, 

 lodicules ; B, flower. The 

 axial parts are repre- 

 sented as elongated. 



glumes come the fertile subtending bracts (PALEA INFERIOR), in the 

 axil of each of which stands a flower. The subtending bracts are 

 often awned, i.e. they bear terminally or springing from the dorsal 

 surface a stiff bristle with backwardly directed hairs (the AWN). The 

 bracteole of each flower is represented by another scale-like bract, the 

 PALEA SUPERIOR. Above this come two small scales, the LODICULAE, 

 the distension of which assists in opening the flower (Fig. 812 .B, C). 

 Lastly, the axis bears the androecium consisting of a whorl of three 

 stamens, and the ovary composed of one carpel and bearing two 

 feathery papillose stigmas. The ovary contains an anatropous, or 

 slightly campylotropous ovule. 



The flowers do not always show such extreme reduction ; thus the flower of 

 Rice (Fig. 817) has a complete androecium ; that of the Bambuseae is similar and 

 also has three lodicules, and in Streptochaeta there is a normal monocotyledonous 

 type of flxnver with all five whorls of members present and three carpels indicated 



