408 SYSTEMATIC BOTANY 



Most Orchids belong to the tropical regions, 

 but they occur in all parts of the world: some, like 

 HABENARIA, on the ground; most, like VANDA, as 

 epiphytes (p. 110) on trees. 



Examples : 



ELUSINE INDICA, Gaertn. the Ragi. The roots are 

 fibrous, and the stems often tufted because branching 

 close to the ground, but they do not branch above it. 

 The leaves are distichous, with a clasping base and long 

 narrow blade, separated by a lighter coloured line along 

 which is a slight ridge of tissue, with short hairs, called 

 the ligule. The veins of the leaf are numerous and 

 parallel, but there is a distinct midrib. 



At the top the stem divides into, or bears, a whorl of 

 five or six branches, and along the outer sides of these 

 are double rows of oval spikelets (why^ ' spikelets ' 

 will be seen later), each consisting of a number of 

 distichously imbricating scales, or glumes, set along a 

 short axis often called the rachilla. With the fingers, 

 or a pair of forceps, the spikelet may be pulled apart 

 between the glumes, except the two lowest, the rachilla 

 being jointed at each one. The glumes are boat- 

 shaped with strong green backs (keels) and scarious 

 sides, the two lowest (fig. 90 C 1 and 2) are empty, but 

 in the axil of each of the others is a thin scarious 

 scale, the palea, with two green veins along which 

 it is folded towards the glume. Between the glume 

 and its palea are the organs of the flower: in the 

 middle an ovary with two styles ; round it three 



