STRUCTURE, MORPHOLOGY, AND PHYSIOLOGY. 15 



they all lie (Streptochceta and perhaps Ochlandra ex- 

 cepted) with their median lines in one and the same 

 plane, and, as in the branches of the culm, this 

 crosses that of the subtending bract, which in this 

 case must be supposed. Where the entire inflorescence 

 ends in an apical spikelet its glumes are naturally 

 arranged like the supposed subtending bract, and there- 

 fore cross those of the lateral spikelets (e.g., Tritkum 

 sativum Lam.). Several genera related to Lolium form 

 an exception to this ; in these genera the median plane of 

 all the glumes coincides with that of the subtending 

 bract. Hordeum and Elyrnus form another, but only an 

 apparent exception ; in these not only do the empty 

 glumes of the 2-3 lateral spikelets converge in front, but 

 their median plane crosses that of the flowering glume at 

 different angles (30°-90°). All these variations depend 

 upon mechanical causes, and are only to allow the 

 glumes of the double or triple spikelets to fit into a given 

 space, since the normal arrangement is present in the 

 solitary terminal spikelets of some species of Hordeum 

 (H crinitum Desf., etc.) and all species of Elyrnus. 



The succession of the flowering of the spikelets should 

 be especially noticed, since in panicles it usually occurs 

 about in that order in which the spikelets emerge from 

 the sheath of the upper leaf ; therefore the terminal 

 spikelets of the panicle and its branches flower first, and 

 from there downwards. In spikes the spikelets situated 

 just above the middle usually precede the others, as they 

 are best developed. In single spikelets, flowering passes 

 from below upwards ; in Panicece and Andropogonece only, 

 if a terminal $ stands below the apparently terminal £ 

 one, it blooms later than the latter. 



Organs of Reproduction. — The Stamens. — The andrce- 

 cium consists of from one to two whorls, each com- 

 posed of from two to three members ; the stamens are 

 rarely (Pariana, Luziola, Ochlandra) more than six (to 

 forty), and in this case apparently spirally arranged. 

 The first stamen of the outer, and usually the only, 

 whorl always stands above the flowering glume ; this 

 is distinguished by the fact that it is earlier and 



