1978 A TEXTBOOK OF THEORETICAL BOTANY 



cotyledon and in the absence of endosperm. In this plant on the other hand 

 the carpels are densely aggregated on the receptacle and the leaves are net- 

 veined. Hutchinson therefore would see in Ranalisma a possible connecting 

 link between the Ranunculaceae on the one hand and the Alismaceae on the 

 other, and therefore between the Monocotyledons and Dicotyledons and 

 a common ancestral type. It is worth noting moreover that both are 

 herbaceous rather than arboreal. 



FARINOSAE (Bromeliales) 



The Farinosae are a small order of Monocotyledons in which the plants 

 are herbaceous and sometimes grasslike. The flowers are hermaphrodite 

 or unisexual, usually trimerous, and composed of a perianth of six segments, 

 six stamens in two whorls, or one whorl of three. Carpels three, united. 



The ovule is usually solitary and often orthotropous and the endosperm 

 usually mealy in character. 



The plants which comprise the order are very various in habit. The 

 Bromeliaceae are essentially xerophytes while the Commelinaceae are 

 tropical and subtropical herbs. The Eriocaulaceae produce flowers in 

 small, terminal capitula, like those of the Compositae among the 

 Dicotyledons. 



The order is split up by Hutchinson into four, in accordance with the 

 more important families. None will be considered here in detail and we 

 shall retain the older method and include them together in Engler's order 

 Farinosae. The families which we shall briefly discuss are Commelinaceae, 

 Eriocaulaceae and Bromeliaceae. 



The Commelinaceae are perennial herbs, bearing leaves with a basal, 

 membranous, closed sheath, covering the young inflorescences. The flowers 

 are usually actinomorphic, rarely zygomorphic, hermaphrodite or rarely 

 polygamous, borne in axillary clusters or in terminal cymes or panicles. 

 The perianth is made up of three sepals and three petals enclosing six 

 stamens, the filaments of which are often hairy. The ovary is trilocular, 

 or sometimes bilocular by suppression, the ovules few and orthotropous. 

 The fruit is a loculicidal capsule. The seeds are large and few in number 

 with a copious endosperm. 



The family includes about thirty genera with nearly 400 species of which 

 the best known are Commelina and Tradescantia. Cojumelina, with about 

 115 species, is widely distributed in the tropics. C. coelestis, with bright 

 blue flowers, is cultivated in gardens. The three inner stamens are sterile, 

 but the filaments contain a sweet juice and are often pierced by bees. 

 C. henghalensis has subterranean cleistogamic flowers. The rhizome in 

 some species is edible. 



The genus Tradescantia contains thirty-five tropical and North American 

 species of which T. virginica (Spider Wort) (Fig. 1909) is the best known. 

 It is commonly grown in gardens on account of its bright purple flowers. 

 The stamen hairs are frequently used in the demonstration of cyclosis. 



