478 



THE DICTIONARY OF GARDENING, 



Dimorphotheca continued. 



from Sin. to Sin. long, entire or slightly toothed. Stein between 

 herbaceous and woody, weak, terete, green, varying in length, 

 simple or slightly branched, h. 1ft. to 2ft. 1861. A rather 

 straggling plant. SYN. Calendula graminifolia. (B. M. 5252.) 



D. lilacina (lilac). A synonym of D. Sarberiee. 



D. Tragus (Tragus). fl. white, purple, opening in the morning 

 and closing again in the afternoon. May, June. (. linear, some- 

 what toothleted, muricate, dotted beneath. Stem suffruticose. 

 h. 2ft. 1774. SYN. Calendula Tragus var. (under which name 

 it is figured in B. M. 1981). 



DINETUS. See Porana. 



DICECIOUS. When a plant bears female flowers on 

 one individual, and males on another. 



DION2EA (from Dionsea, a surname of Venus, as the 

 supposed daughter of Jupiter and Dione). OBD. Drose- 

 raceoe. A dwarf, exceedingly interesting, herbaceous 

 perennial. It thrives in a mixture of peat and living 

 sphagnum. The pot containing it should be placed in a 

 pan of water, and stood near the glass in the greenhouse, 

 or even in a cold frame. Propagated by division of the 

 plant, or sometimes by seed. 



D. mnscipula (fly-catcher).* Venus's Fly-trap, fl. white, in ter- 

 minal corymbs. July and August. I. radical, on long footstalks, 

 which are dilated at the top into a two-lobed irritable limb, 

 beset with one row of long hairs on the margin, folding 

 together, in the manner of the teeth 

 of a trap. h. Sin. to 6in. Carolina 

 and Florida, 1768. The seat of irri- 

 tation resides in the three bristles 

 which are placed in the centre of 

 each lobe ; on these being touched, 

 movement immediately takes place. 

 See Fig. 669, page 477. (B. M. 

 785.) 



DIOON (from die, two, and 

 oon, an egg; in reference to each 

 scale bearing two ovules ; other- 

 wise from the seeds being borne 

 in twos). SYN. Platyzamia. OBD. 

 Cycadacece. A very singular genus 

 containing a couple of species, 

 both natives of Mexico. They 

 make noble objects in a collec- 

 tion of ornamental-leaved plants. 

 Dioons thrive best in a compost 

 of good loam and river sand, 

 and succeed well in an ordinary 

 greenhouse, except when in a 

 growing state, at which period 

 they should have the warmth of 

 a stove. Propagated by seed, 

 which are very large. Miquel 

 observes that this genus is more 

 closely allied to certain fossil 

 Cycadacece than is any other 

 living representative of the 

 order. 



D. ednle (edible).* I. glaucous-green, 

 pinnate, from 3ft. to 6ft. in length, 

 and 6in. to 7in. in breadth, tapering 

 towards the base, where they are 

 clothed with short white woolly 

 hairs ; texture very firm. Stems 

 about 3ft. in circumference, h. 3ft. 

 1844. (B. M.6184.) The fruit of this 

 plant is as large as a chestnut, and 

 is powdered by the natives, and 

 formed into a kind of arrowroot. 



DIOSCOREA (named after 

 Dioscorides, a native of Ana- 

 zauba, in Cilicia, who lived in 

 the age of Nero; his celebrated book upon medicinal 

 herbs was the foundation of almost all botanical know- 

 ledge until modern times). Yam. OBD. Dioscoreacece. 

 Very ornamental-leaved (with few exceptions) stove her- 

 baceous climbers, with large tuberous roots, admirably 

 adapted as trellis or pillar plants. Flowers whitish or yel- 

 lowish, inconspicuous. Leaves broad, cordate, or angular. 



FIG. 670. DIOSCORKA 

 BATATAS. 



Dioscorea continued. 



In the winter months, Dioscoreas should be kept in a 

 cool (but not cold) place, either in the pots or in some 

 perfectly dry sand. The most suitable soil is a rich light 

 compost, formed of turfy loam and well-decomposed 

 manure, in about equal parts. They should have abund- 

 ance of root room, and be liberally supplied with water 

 during the growing season, gradually diminishing the 

 quantity as the shoots show signs of decay. Propa- 

 gated by divisions of the tubers, which may be effected 

 either in autumn or spring, while they are at rest, but 

 never when growing. 



D. An03OtocbUns(Ano3ctochilu8-like). I. deep olive-green, beau- 

 tifully marbled with gold, with a central band of the same colour, 

 broadly acuminate ; when young, they are of a uniform plain 

 bright green. South America, 1865. 



D. argyraa (silvery). I. green, cordate, about Sin. across, 

 seven-nerved ; nerves bordered with distinct irregular angular 

 patches of silvery -grey. Columbia. 



D. Batatas (Batatas).* Chinese Yam. fl. white, dioscious, very 

 small, in axillary racemes, generally sterile. I. deep green, very 

 glossy, opposite, cordate, acuminate. Stems annual, smooth, 

 green or purplish, sometimes attaining a height of from 6ft. to 9ft. 

 The roots are used like potatoes boiled, roasted, and cooked in 

 various other ways. Probably the great depth to which the tubers 

 descend, and the consequent expense of harvesting the crop, has 

 prevented this useful hardy vegetable from being much cultivated 

 in this country. See Fig. 670. 



D. bulbifera (bulb-bearing).* fl. greenish, disposed in gracefully 

 drooping racemes. I. broad, cordate. East Indies, 1692. A very 

 old inhabitant of our stoves, and at one time strongly recom- 

 mended as a substitute for the potato. (G. C. n. s., vih 48.) 



PIG. 671. TUBERS OF DIOSCOREA DECAISNKANA. 



D. Decalsneana (Decaisne's). Decaisne's Yam. I. very light 

 green, opposite or alternate, deeply cordate at base, regularly 

 narrowed to the apex. Tubers in some cases smooth and regu- 

 larly shaped, as in some varieties of potato, others very irregular. 

 China, 1862. Perhaps this is a variety of D. Batatas, from which 

 it, however, differs a good deal in the tubers not being developed 

 at such a great depth underground. See Fig. 671. 



D. discolor (two-coloured). I. beautifully mottled with two or 

 three shades of green, large, cordate ; under surface rich purplish- 

 crimson. Tropical America. 



D. illustrata (illuminated). I. satiny-green, marked by fine 

 transverse whitish parallel lines between the nerves, with an 

 irregular central band of silvery-grey, and a few angular patches 

 of the same colour, generally placed in juxtaposition with the 

 ribs ; about 6in. long, produced at the base into two bluntish 

 lobes ; under surface purple. Brazil, 1873. (G. C. 1873, 1730.) 



D. multicolor (many -coloured).* I. rich green, beautifully spotted 

 and variegated with pale spots and blotches, most numerous 

 near the principal veins; cordate, 3in. to Sin. long, and 2iin. to 

 Sin. wide ; under surface pale lurid purple. Bio Negro, 1868. 

 (I. H. 1871, 53.) There are about half-a-dozen varieties of this 

 species known, of which the following are in cultivation : chryso- 

 phylla, leaves olive-brown, variegated with yellow ; Eldorado, 

 leaves satiny-green, with silvery-grey central band, and irregular 

 blotches of the same colour; melanoleuca, leaves deep green, 

 with central silvery band and silvery blotches along the veins ; 

 metallica, leaves bronzy, with coppery central band. 



D. nobilis (noble). I. velvety-bronze, variegated with yellow. 

 Brazil, 1868. 



D. retusa (retuse). fl. dull yellowish ; racemes axillary, slender, 

 pendulous, many-flowered. I. alternate, loosely scattered, digi- 

 tate ; leaflets five to seven, petiolulate. South Africa, 1870. 

 (G. C. 1881, xv. 511.) 



D. sativa (cultivated). Common cultivated Yam. I. alternate, 

 cordate, round, ovate, cuspidate ; lobes of base close together. 

 Stem smooth, round, slender. West Indies, 1733. 



D. vlttata (striped). I. flushed with claret-colour beneath, or 

 variegated with red and white on both sides, large, cordate. 

 (B. M. 6409.) 



