DIOSCOREA 



THE BULB BOOK 



DIOSCOREA 



This species flourishes in warm 

 sandy loam, and should be planted 

 in sheltered positions, as it is not 

 hardy in the bleaker parts of the 

 Kingdom. When grown in bold 

 masses, the blood-red blossoms con- 

 spicuously swaying in the breeze look 

 particularly bright. The bulbs should 

 be planted about 3 ins. deep on 

 raised beds of well - drained soil 

 between November and January, 

 after the leaves have withered. 

 During severe weather, the roots 

 should be protected with a covering 

 of straw, litter, or bracken; but in 

 spring, when growth commences, as 

 much light and air as possible should 

 be given. 



DIOSCOREA (after Dioscorides, 

 whose book on medicinal herbs " was 

 the foundation of almost all botanical 

 knowledge "), YAM. Nat. Ord. Dios- 

 coreaceae. This genus' consists of hot- 

 house plants, having large tuberous 

 roots, climbing or trailing stems, and 

 large heart-shaped or angular leaves, 

 which in most species are ornamental 

 in character. Unlike most members 

 of the monocotyledonous group, the 

 leaves also are reticulately instead of 

 parallelly veined. The small whitish 

 or yellow flowers are of no garden 

 beauty, the perianth consisting of six 

 small distinct segments. From an 

 economic point of view, the West 

 Indian Yam (D. sativa) is perhaps 

 the best known and the most useful. 

 It has alternate, heart - shaped, 

 roundish leaves ending in a point, 

 and borne on smooth, round, slender 

 stems. D. Batatas, the Chinese Yam, 

 has heart-shaped, pointed, deep glossy 

 green leaves on green or purplish 

 stems 6 to 9 ft. long. The long 

 club-like roots are used like potatoes, 

 after being boiled, roasted, or other- 

 wise cooked. D. Decaisneana, another 

 Chinese Yam, is a variety of D. 



Batatas, having pale green, heart- 

 shaped leaves, deeply lobed at the 

 base, and regularly narrowed to the 

 apex. The tuberous roots, however, 

 are much smaller than those of D. 

 Batatas, and do not penetrate so 

 deeply into the soil. 



Amongst species of Yam with 

 beautiful foliage, mention may be 

 made of the following : 



D. Anoectochilus, from S. America, 

 has deep olive-green leaves beautifully 

 marbled with gold, with a central 

 band of the same colour. 



D. argyrea, from Colombia, has 

 green heart-shaped leaves about 5 

 ins. across, with seven main veins 

 bordered with conspicuous irregular 

 patches of silvery grey. 



D. bulbifera, introduced from the 

 East Indies in 1692, was at one time 

 strongly recommended as a substitute 

 for the potato. The leaves are large 

 and heart-shaped, and the small 

 greenish blossoms are borne in grace- 

 fully drooping racemes. 



D. caucasica. A graceful Caucasian 

 climber, having the lower leaves in 

 whorls of three to five, the upper 

 ones being almost opposite. It is 

 very like the Black Bryony (Tamils 

 communis) in appearance. (Gard. 

 Chron. 1894, xv. 778.) 



D. crinita, [from Natal, has long- 

 stalked leaves, divided into five 

 elliptic lance - shaped leaflets, each 

 ending in a long thread-like point 

 (Bot. Mag. t. 6804). 



D. discolor. A native of Tropical 

 America, having large heart-shaped 

 leaves, elegantly marbled with two 

 or three shades of green on the upper 

 surface, the under-surface being rich 

 purple-crimson. 



D. Fargesi, from W. China, has 

 edible tubers (Rev. Hort. 1896, 540). 



D. hybrlda. This plant is supposed 

 to be a hybrid between the Chinese 

 Yam (D. Batatas) and the British 



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