Studies of Selected Spermatophytes. 219 



The form of the plant is interesting, since it is plainly 

 adapted to its submerged habitat (see page 323). Take 

 fresh plants from water and note how quickly they dry up. 

 The lack of a waterproof epidermis probably enables this 

 plant to absorb gases in solution throughout its surface. 



Do the seeds float when ripe, or sink at once to the 

 bottom ? 



This is apparently one of the lowest of the Monocotyle- 

 dons. Its simple staminate and pistillate flowers remind 

 one of the sporangia of Pteridophytes, and it seems to be 

 on the direct line of ascent from Pteridophytes to Sperma- 

 tophytes. The evidence, however, is not sufficient for a 

 definite conclusion. 



Arisaema triphyllum. 



Make a drawing to show the habit of the entire plant. 

 What terms would you apply to the leaves as to their 

 habit and form ? Are they simple or compound, radicle or 

 cauline ? (See Glossary.) The enlarged underground part 

 is a corm stored with reserve food. 



The inflorescence is unique. The slender, naked pedun- 

 cle is called a scape. The leaf-like envelope of the inflores- 

 cence, funnel-shaped below, overarching above, is termed 

 a spathe. The fleshy floral axis inclosed in the spathe is 

 called a spadix. 



The flowers are very simple and destitute of a perianth. 

 A single staminate flower consists of four stamens, and a 

 pistillate flower of a single pistil. Note whether they are 

 monoecious or dioecious, proterandrous or proterogynous 

 (see Glossary). 



Make a drawing of an inflorescence with the spathe cut 

 away on one side to reveal the interior. Halve a pistil 

 longitudinally and draw the ovules in position. Draw a 



