THE MONOCOTYLEDONES 



1991 



water, thereby blocking water courses. They are common in Florida and 

 South America and have become naturalized in India, Java and Australia. 



The genus Pontederia is represented by P. cordata, the Pickerel Weed, 

 a hardy garden plant, native of North America. 



The family is exceptional in the Liliales in having an irregular corolla. 

 There are six unequal segments in two whorls, the inner posterior segment 

 being enlarged. The ovary is also notable, two of the three carpels being 

 sterile and the third uniovulate. 



The Smilacaceae ditfer from the other families of the Liliales in 

 having mostly dioecious flowers and in their climbing habit. The family 

 includes four genera of which Smilax itself is the best known. There are 

 over 300 species which are widely distributed in tropical and subtropical 

 parts of the world. They are mostly climbing shrubs with net- veined leaves. 

 At the base of the leaf are a pair of tendrils which have been variously 

 interpreted, though most often as modified stipules (see \^olume I, p. 1037). 

 The stems are often beset with curved hooks as a further means of climbing. 

 The flowers are dioecious and are produced in umbels. The dried roots 

 of several species are the source of Sarsaparilla. S. china provides the 

 material known as China Root used locally in medicine. 



The Ruscaceae are another small family in which the plants are either 

 climbers or woody shrubs. The leaves are reduced to scales while axillary 

 branches are modified as cladodes bearing small flowers either on their 

 adaxial surfaces or on their margins. They are restricted to western Europe 

 and the Mediterranean region (Fig. 1922). They difi^er from the Liliaceae 

 in having united stamens. There are three genera, Danae, Semele and 

 Rusciis. One species of Semele is found in the Canary Islands; it is a climbing 



Fig. 1922. — Distribution of i?!/xcM^. {After Hutchinson.) 



