DION] 



l&fyz Ercatfurp of 23d tang. 



410 



DI01SLEA. A singular plant referred to 

 in most works on structural and physio- 

 logical botany, as affording a striking in- 

 stance of vegetable irritability, B. musci- 

 pula, Venus's Flytrap, the only species, 

 belongs to the order Droseracece, and is an 

 humble marsh plant bearing from the root, 

 on a smooth leafless stalk a few inches high, 

 a corymb of white flowers. The root is 

 composed of scales almost like a bulb 

 with a few fibres. From this proceed in a 

 radiating manner a number of leaves on 

 lougish stalks, which are winged like those 

 of the orange-tree. The lamina of the leaf 

 itself is divided by the midrib into two 

 nearly semicircular halves, each of which 

 is fringed with stiff hairs, and furnished 

 near the middle with three minute bristles 

 arranged in a triangle, which bristles are 

 extremely irritable, and when touched by 

 a fly or other insect cause the two sides of 

 the leaf to collapse with a sudden spring, 

 imprisoning the intruder until it is either 



Dionsea muscipula. 



dead or ceases to move. Some time after 

 all motion has ceased, they open again 

 spontaneously. It is a native of the 

 swamps of North Carolina, but is often 

 cultivated in English stoves. Biomsa is 

 derived from Dione, one of the C4reek 

 names of Venus : muscipula is in Latin ' a 

 fly-trap.' As might be expected, the same 

 result is produced by touching the irri- 

 table bristles with any fine-pointed sub- 

 stance, as a pin or bit of straw. French, 

 L'attrape-mouche : German, Venus die flie- 

 genfungerin. [C. A. J.] 



DIONYSIA. A genus of Prhnulacece, 

 closely allied to Gregoria, and including 

 all the Oriental species previously de- 

 scribed under the latter name, but dis- 

 tinguished by Boissier from the European 

 G. vitaliana on account of some slight 

 differences in the seeds and in the shape 

 of the corolla. They are all small Alpine 

 tufted plants, with flowers intermediate 

 between those of a Primula and of an 

 Androsace. 



DION. A family of Mexican Oycadeacem 

 with a simple Zamia-like stem clothed 

 with woolly hairs, and bearing light-green 

 pinnate leaves, whose leaflets are sword- 

 shaped, very sharp, attached to the petiole 



by their whole base. The female cone is 

 about the size of a child's head, and con- 

 sists of flat lance-shaped scales, covered 

 with wool, and two-lobed at the base ; each 

 scale bears two large seeds of the size of 

 chestnuts. The seeds of B. edule yield a 

 large quantity of starch which is used as 

 arrowroot. [M. T. M.] 



DIORYCTANDRA. This name, whicli 

 has but slender claims to euphony, is ap- 

 plied to a shrub of the violet family, in 

 allusion to the passage of the style through 

 the anthers. The genus is closely allied 

 to Alsodeia from which it differs in the 

 greenish petals, which are stalked, not 

 sessile ; and in the stamens which have 

 slender filaments as long as the stalks of 

 the petals. [M. T. M.] 



DIOSCOREACEiE. (Yams.) A natural 

 order of monocotyledonous or Endogenous 

 plants belonging to the subclass of Bictyo- 

 gence. Twining shrubs or herbs with 

 tubers either above or below ground, usu- 

 ally alternate leaves with reticitlated vena- 

 tion, and small staminate and pistillate 

 flowers growing in spikes. Perianth six- 

 cleft, in two rows, herbaceous and adhe- 

 rent ; stamens six, inserted into the base 

 of the perianth ; ovary inferior, three- 

 celled ; ovules one or two, suspended ; style 

 three-cleft. Fruit compressed, three-celled, 

 two cells often abortive ; seeds albumin- 

 ous ; embryo in a cavity. They are found 

 chiefly in tropical countries. Tamus is, 

 however, a native of Europe and of the 

 temperate parts of Asia. 



Acridity prevails in the order, but it is 

 often associated with a large amount of 

 starch. Various Bioscoreas produce edible 

 tubers, which are known as yams and are 

 used like potatoes. Tamus communis, 

 black bryony, has an acrid purgative and 

 emetic tuber, and a berried fruit of a red 

 colour. Testudinaria Elephantopis has a re- 

 markably tuberculated stem, and has been 

 called elephant's foot or the tortoise-plant 

 of the Cape. The central part is eaten by 

 the Hottentots. There are seven genera 

 and 160 species. Tamus, Testudinaria, 

 and Bioscorea, are examples. [J. H. BJ 



DIOSCOREA. The typical genus of the 

 order of yams. Upwards of 150 species 

 are described, most of them being confined 

 to tropical countries, principally in Ame- 

 rica and Asia, the majority, however, be- 

 longing to the former continent ; about a 

 dozen are found in Africa, and three or 

 four in Australia. They are herbaceous 

 perennials qr undershrubs, with twining 

 stems generally turning to the left hand ; 

 and fleshy tuberous roots : their leaves 

 are usually produced alternately, but occa- 

 sionally opposite, and, except in a few spe- 

 cies where they are divided into several 

 radiating lobes, they are always entire, 

 and have several strongly-marked veins 

 running throughout their entire length. 

 The flowers, which are very small and in- 

 conspicuous, are produced in spikes from 

 the bases of the leaves, and consist of a 

 perianth of variable form, but usually 



