DIV. n ANGIOSPERMAE 627 



covered with warty prickles, and bears three large, bifid, red stigmas. In each 

 loculus of the fruit is a mottled seed with a whitish caruncula. 



OFFICIAL. Croton Eleuteria (Bahamas) yields CASCARILLA. C. tigliurn (East 

 Indies), OLEUM CKOTONIS. OLEUM RICINI, Castor Oil, is obtained from Ricinus 

 communis. 



Order 10. Centrospermae 



Plants with as a rule hermaphrodite flowers which approximate to 

 the typical dicotyledonous flower. 



Family 1. Chenopodiaeeae. Perennial or annual herbs, rarely 

 small woody plants, with alternate leaves. Flowers typically 

 pentamerous, with a single whorl in both perigone and androecium ; 

 P 5, A 5, G (2-5). % Stamens opposite the perianth leaves. Eeduced, 

 unisexual flowers*are not infrequent. The unilocular ovary contains 

 a basal, campylotropous ovule. Fruit, a nut. Seed with a curved 

 embryo bent around the floury perisperm. 



Many of the Chenopodiaeeae are strand plants or occur on soils containing a 

 large amount of salt, such as the great Asiatic salt steppes and deserts. The 

 Spinach (Spinacia oleracea) and the Summer Spinach (S. glabra) are used as vege- 

 tables. The Sugar Beet (Seta vulgaris, var. rapa) is a plant of great economic 

 importance. It is a biennial plant, and in the first season forms a thick, swollen 

 root bearing a bud consisting of a number of thick-stalked, entire, succulent, and 

 often crisped leaves. From this rosette of leaves there springs in the second season 

 a highly branched panicle, bearing the inconspicuous greenish flowers. Ovary 

 formed of three carpels. At the end of the first season the root contains cane-sugar 

 as a reserve material, which at this stage is extracted from the plant. By constant 

 selection the percentage of sugar is raised from 7-8 % to an average of 14 % ; it may, 

 however, reach 21-26 %. The original form of the Sugar Beet is Beta patula. 

 Chenopodium and Atriplex are common weeds near human dwellings. 



Family 2. Caryophyllaeeae. Annual or perennial herbs, with 

 simple, linear, usually opposite leaves ; flowers typically pentamerous, 

 with calyx a-nd corolla. Two whorls of stamens, obdiplostemonous. 

 Unilocular or incompletely septate ovary. K 5, C 5, A 5 + 5, G (5) 

 (Fig. 630). Fruit, a capsule. Seeds numerous, embryo curved around 

 the floury perisperm. 



Ccrastium and Stellaria have white flowers and bifid petals, and are conspicuous, 

 early-flowering forms. Species of Dianthus, Pinks, have frequently attractive 

 colours and scent, and occur in dry sunny situations. Agrostemma Githago 

 (Fig. 628), Corn-cockle, is a hairy plant with pink flowers ; it is a common weed 

 in corn-fields. Since its seeds are poisonous, their mixture with the grain may have 

 serious results. Saponaria qfficinalis is a herb attaining the height of a metre, 

 with opposite, broad leaves and rose-coloured flowers. The saponin contained 

 in all parts of the plant renders it poisonous (Fig. 629). 



Family 3. Aizoaceae. Perennial herbs or small shrubs, usually with suc- 

 culent leaves. Flowers hermaphrodite ; with simple perianth or with a calyx and 

 a polypetalous corolla derived from modified stamens. Stamens numerous. Carpels 

 2-oo ; united to form the hygroscopic capsule. 



2S 1 



