536 



BOTANY 



r.M.r ii 



Acorus calamus has, in the course of the last two or three centuries, spread to 

 this country from the East. It has complete, hermaphrodite flowers; ovary tri- 

 locular. The short spadix is terminal, but is displaced to one side by the sp.it he. 

 which resembles the foliage leaves (,Fig. 532). 



POISONOUS. Many Araceae are poisonous. Calla palustris in peaty swamp-. 

 Arum maculatum (Fig. 533), a perennial herb with tuberous rhizome, common in 

 woods. It develops a number of stalked, ha.-taie leaves, the brown spots on which 

 give the plant its specific name. The flowers are monoecious, without perianth ; 

 the female flowers stand at the base of the spadix and the male a short distance 

 above them. Above the latter come a number of sterile flowers with downwardly 

 directed, hair-like j mints, which stand at the level of the constricted i>ortion of the 

 spathe ; this is widely open above. These hairs allow insects, attracted by the 

 peculiar scent or seeking warmth (cf. p. 244), to creep into the lower expanded 

 portion of the spathe, but prevent their return until the female flowers have been 

 pollinated from another individual. When this is accomplished the hairs wither 

 and the anthers open. The escaping insects, now dusted with pollen, may enter 

 other inflorescences and pollinate the flowers. 



Family 6. Lemnaceae. The Duck-weeds of our ponds and streams have naked 

 monoecious flowers borne in depressions of the body of the plant. The flowers are 

 surrounded by a small spathe. Lemna, Wolffm. 



Order 4. Enantioblastae 



A small order. Ovules orthotropous ; embryo at summit of endosperm at 

 opposite end from the hilum. 



Family Conimelinaceae. Peri : 

 anth developed as calyx and corolla. 

 The hairs of the stamens all', rd 

 well-known objects for the study 

 of movements of protoplasm and 

 nuclear divisions. Fruit a capsule. 



Comineliiia, Ti'in 



Flo. 534. Diagram nt'u typical I.iline.'<>ii> 

 flower. 



I-li.. . liinij'i-iH-iir/iii*. a, 1'jirt lit' an 



illtldl-escelice I single fll IWcr (h) ;ill'l .H.MI - 



aeceiun (<) iim^nilifil. 



Order 5. Liliiflorae 



Flowers actinomorphic, composed of five whorls, \\ith superior or 

 inferior ovary. Both whorls of the perianth developed alike. Only 



