LESSON VII 



PEDICELED ONE-FLOWERED SPIKELETS 



TURN to the spikelet of wild oats (Fig. 31) and in 

 imagination eliminate all but the lowest floret and 

 the glumes. Better still, with a spikelet of oats in 

 hand break off all above the lowest floret. Now we 

 have a large model or pattern of the reduced spikelet 

 of a very large number of grasses, red-top, timothy, 

 and their kind. 



Examine Calamagrostis canadensis (Fig. 35, the 

 floret raised from its glumes) and note how it corre- 

 sponds to the pattern obtained 

 by reducing the spikelet of oats 

 to a single floret. The only 

 vestige remaining of the other 

 florets is the minute rachilla 

 joint back of the palea (shown, 

 exaggerated somewhat, in Fig. 

 35). In all but a few genera the 

 rachilla is entirely suppressed. 

 Compare Fig. 35 with Fig. 32 

 and note that Trisetum reduced to a single floret 

 would closely resemble Calamagrostis. 



In Agrostis (Fig. 36) the rachilla is normally 

 suppressed. In two species in the far West it is 

 present as a minute rudiment. In most of the species 



46 



FIG. 35. Spikelet of Cala- 

 magrostis canadensis. 



