LESSON VIII 

 SESSILE SPIKELETS IN ONE-SIDED SPIKES 



As stated in Lesson V, development does not follow 

 a single line, so, having come to the end of one line, 

 we must repeatedly return to the center and start in 

 a new direction. In the group of grasses taken up 

 in this lesson the principal character common to 

 all is the spicate inflorescence. In the grasses related 

 to barley (Lesson V) we found solitary 2-sided spikes, 

 the spikelets sessile on opposite sides of the rachis. 

 In the present group we have 1-sided (unilateral) 

 spikes, the spikelets sessile or nearly so along one 

 side of the rachis. The spikelets themselves range 

 from the simple one of yard-grass, Eleusine indica 

 (Fig. 47), to highly specialized ones. Compare 

 Fig. 47, A, with Figs. 11 and 14. It will be seen that, 

 although the glumes and lemmas of Eleusine are 

 strongly keeled, the spikelets are of the same type; 

 but these spikelets are very differently arranged 

 (Fig. 47, B), being crowded and imbricate (over- 

 lapping like shingles) in two rows on one side of the 

 rachis. Two to several of these spikes are borne 

 together, digitate or nearly so. [Digitate means 

 arranged like fingers (digits), but as a botanical 

 term it indicates an arrangement more like that 



54 



