370 



THE PANDANALES 



become filled with water, there can be no interchange of gases 

 for photosynthesis during this time. 



The flowers are of a very primitive type, consisting of naked 

 sporophylls arranged in a compact inflorescence that assumes a 

 spike-like structure at the tip of the stem. The sporophylls are 

 protected until mature by modified sheathing leaves (Fig. 280, A). 

 Each flower in the upper portion of the spike contains only two 

 or three stamens supported upon a short stalk, which is asso- 

 ciated with hair-like outgrowths (Fig. 280, 5), while the lower 



FIG. 280. 



FIG. 281. 



FIG. 280. Inflorescence and fruit of Typha: A, inflorescence b, pro- 

 tecting bracts curving away from the sporophylls ; mi, region of staminate 

 flowers ; mg, region of pistillate flowers. B, staminate flower consisting of 

 two stamens sessile upon a short stem. C, pistillate flower of one carpel 

 s, stigma; o, ovary containing a single ovule. D, appearance of A in the 

 fall mi, region occupied by staminate flowers; mg, the pistils have in- 

 creased greatly in size during the ripening of the seed. 



FIG. 281. The mature fruit of Typha: s, remains of the stigma; o, 

 ovary; p, elongated pedicel bearing numerous hairs. Compare Fig. 280, C. 



