496 A TEXT-BOOK OF BOTANY. 



I per cent, of volatile oil containing phellandrene and turmerol ; 0.3 

 per cent, of a yellow crystalline principle, curcumin, which is 

 soluble in alcohol, sparingly soluble in water, forms reddish-brown 

 solutions with alkalies and is converted into vanillin with, weak 

 oxidizing agents. It also contains considerable starch and a small 

 quantity of an alkaloid. 



Other families of the Scitaminese are of great importance on 

 account of the food-products obtained from them, as the Miisa- 

 cece, which contains the group of plants to which the ranaxa 

 (Musa paradisiaca and M. Sapientum) belongs. To the Canna- 

 cecc belong the cultivated Cannas, one of them, Canna edulis, 

 being grown extensively in the West Indies and Australia as a 

 vegetable, and another, Canna coccinea, which grows in the West 

 Indies and South America, furnishing " Tous les mois," the 

 arrow-root starch of the English and French. To the Maranta- 

 cece belongs Maranta arundinacea, which is cultivated in tropical 

 America, and the rhizome of which yields the starch, Maranta 

 ARROWROOT (Fig. 88, B), and is largely used in the preparation of 

 infants' food. 



IX. ORDER ORCHIDALES OR MICROSPERM^. 



The most important family of this order is the Orchidace.e or 

 Orchid Family. The orchids are the most highly specialized 

 of the Monocotyledons. They are perennial herbs with diverse 

 habits, many tropical species being epiphytes, and of varying mor- 

 phological structure, which is particularly evident in the zygo- 

 morphic flowers. The perianth consists of 6 segments. The 3 

 outer correspond to sepals and are similar. Two segments of the 

 inner circle correspond to petals and are alike, while the third, 

 which is known as the lip, is remarkably modified, being usually 

 larger, often spurred, and frequently reversed, being turned for- 

 wards and downwards by the twisting or torsion of the ovary. 

 Only one of the stamens — the anterior of the external whorl — is 

 developed and bears an anther. The other stamens are entirely 

 wanting or present as staminodes (except in Cypripedium and the 

 Apostasieae). The filament is united with the style to form a 

 column, the so-called " stylar v'^lumn," and the anther is thus 

 placed on its apex, and behind the stigma. The 3 carpels form a 

 unilocular ovary with 3 parietal, deeply bifid placentae. TJie fruit 



