2oi6 A TEXTBOOK OF THEORETICAL BOTANY 



long-stalked, short, cylindrical spadix, subtended by a broad spathe. The 

 inflorescence emits a nauseous odour. The flowers are protogynous. From 

 thirty to fifty stigmas appear in the first stage of anthesis as small whitish, 

 strongly papillose and viscous circles on the ovaries. The lower ones are 

 receptive as soon as the spathe opens. The anthers dehisce only when some 

 of the stigmas have shrivelled. In the first stage they are sessile but later 

 they develop short stalks. Pollination is effected by various insects, parti- 

 cularly small flies, though snails have been observed to feed on the pollen. 

 The ovary is unilocular and from its base there arise from six to nine 

 anatropous ovules. 



Belonging to the sub-family Lasioideae is the genus AmorphophaUus 

 (Fig. 1953) with some ninety species from tropical Asia. Usually the 

 rhizome produces yearly a single leaf up to 10 ft. in length and an 

 inflorescence which may be several feet long. It is made up of male 

 flowers above and female flowers below. It is a dirty red in colour and the 

 foetid smell attracts carrion flies which serve as pollinators. A. variabilis 

 is said to be pollinated by snails. The genus Dracoritium with ten species is 

 similar in structure but occurs in America. In D. gigas the leaf may be 

 15 ft. high; it has a long stem-like petiole and a three-branched lamina. 



In the Philodendroideae is included Zantedeschia, a small South African 

 genus, species of which are commonly cultivated under the name Richardia 

 (Fig. 1954), the Arum Lily. They have thick rhizomes and large sagittate 



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Fig. 1954. — Richardia africana. Arum Lily. 

 Spadix surrounded by the pure white 

 spathe. 



