DIDl'SCUS. 



84 



dillwy'nia. 



the seeds of which separate into two 

 cotyledons, or seed-leaves, when they 

 vegetate : and this class comprehends 

 three-fourths of all the known plants 

 in the world. They have all reti- 

 culated leaves, that is, leaves the veins 

 in which appear like net-work when 

 held up to the light ; and the ligne- 

 ous species have the thickness of their 

 sterns increased every year by suc- 

 cessive layers of new wood, deposited 

 on the outside of the old wood, im- 

 mediately under the bark. In all 

 these points, and many others less 

 conspicuous, they differ from the 

 monocotyledonous plants, or those 

 the seeds of which have only one 

 seed-leaf, or cotyledon. 



Dicta'mnus. — Rntacece. — Fraxi- 

 nella. There are two species, the 

 purple and the white, both hardy per- 

 ennials, and both natives of Ger- 

 many. The leaves have a pleasant 

 smell, like lemon peel, when rubbed, 

 and the plant emits a phosphoric 

 vapour, which may be easily ignited 

 by a candle, and burns like gas. The 

 flowers are very ornamental ; and the 

 plants will grow in any common gar- 

 den soil, and in any situation not im- 

 mediately under the drip of trees. 

 They are increased by division of the 

 root. 



Dim'scus. — UmbeWfertE. — The 

 beautiful Australian plants, some- 

 times called by this name, and some- 

 times by that of Trachymene, are 

 half-hardy annuals, that require to 

 be raised on a hot-bed, and not 

 planted out till May or June. In very 

 cold, exposed situations, they are gene- 

 rally grown in pots, and kept in the 

 green-house ; but they never flower 

 so well as in the open ground. The 

 best way to grow them is to sow the 

 seed in autumn as soon as it can be 

 procured from the seed shops, on a 

 slight hot-bed, to pot the plants as 

 soon as they have formed their second 

 pair of leaves, and to keep the plants 



in a frame or green-house, shifting 

 them occasionally, till the following 

 spring, when they may be planted in 

 the open ground in a light rich soil, 

 and they will flower beautifully. 



Diervi'lla. — Caprifoliacece. — 

 A little North American shrub, with 

 yellow flowers something like those 

 of the honeysuckle in shape. It was 

 formerly considered to belong to Lo- 

 nicera. It is very hardy, and will 

 grow in almost any soil or situation, 

 sending up abundance of suckers, by 

 which it is easily increased. 



Digging. — The art of pulverising 

 the ground so as to reduce it to a fit 

 state to be penetrated by the roots of 

 plants ; and also to render it pervious 

 to the rain and air, without the aid of 

 which neither seeds could vegetate, 

 nor trees grow. Digging, (or plough- 

 ing, which is the same thing on a 

 larger scale,) is the first operation per- 

 formed by man on a barren waste 

 when he takes it into cultivation. 



Digita v lis. — Scrophularince. — 

 The Foxglove. If this plant were 

 not a common British weed, it would 

 be thought very ornamental ; and, in 

 fact, the Teneriffe species, D. cana- 

 riensis L., (Isoplexis canariensis 

 G. Don), with yellow flowers, and D. 

 sceptrum L., (I.sceptrum G. Don,) 

 with orange flowers, are favourite 

 green-house shrubs. They should be 

 grown in a mixture of loam and peat, 

 and mav be propagated by cuttings or 

 seeds which they ripen in abundance. 

 The hardy herbaceous species which 

 modern botanists have left in the 

 genus Digitalis, are mostly natives of 

 the south of Europe, and are all or- 

 namental. They require a light rich 

 soil, and are propagated by seeds. 



Dillwy'nia. — Leguminosce. — 

 Australian shrubs with heath-like 

 leaves, and pea- flowers, which are 

 generally scarlet and orange. They 

 should be grown in pots well drained, 

 and in a mixture of peat, loam, and 



