ENCYCLOPAEDIA OF HORTICULTURE. 



475 



Dieffenbachia continued. 



D. triumphans (triumphant). I. dark green, covered with large, 

 irregular, angular, yellowish-green blotches, somewhat spread- 

 ing, ovate-lanceolate, attenuately acuminate, about 1ft. long, and 

 4in. to 5in. wide. Columbia. A very ornamental species. 



D. velutina (velvety). /. satiny-green ; petioles white. Columbia, 



D. yerschaffeltii (Verschaffelfs). A synonym of D. Bara- 



quimana. 

 D. vittata (striped). I. greyish-green, with two feathery white 



bands. Tohma. 



D. Wallisii (Wallis's).* I. ovate-lanceolate, of a rich dark green, 

 marked along the midrib with broad feathery bands of a light 

 grey, ornamented with irregular blotches of the same colour to- 

 wards the margin. Columbia, 1870. (I. H. 1870, 11.) 

 D. Weiril (Weir's). I. bright green, thickly blotched and spotted 

 with pale yellow. Brazil, 1866. A fine species, of dwarf habit 

 DIELYTRA. This name, by an erroneous conjecture, 

 was changed from Diclytra, in the first instance acci- 

 dentally printed for Dicentra (which see). 



DIERAMA. See Sparaxis pendula and S. pul- 

 cherrima. 



DIERVILLA (named in honour of M. Dierville, a 

 French surgeon). STN. Weigelia. OBD. Caprifoliacece. 

 A genus of very handsome hardy 

 shrubs. Flowers white, purple, 

 pink, or yellow, in axillary and 

 terminal clusters ; corolla fun- 

 nel-shaped or campanulate ; tube 

 regular. Leaves opposite, ses- 

 sile, or petiolate, serrated. These 

 elegant shrubs are of very easy 

 culture in common garden soil, 

 if the situation is a rather moist 

 and shaded one. Propagation 

 may be readily effected by cut- 

 tings, made in spring or autumn, 

 or by the freely-produced suckers. 

 The gracefully spreading form of 

 Diervillas renders them remark- 

 ably well adapted for shrubberies ; 

 and D. grandiflora, in particular, 

 can be very successfully grown 

 as a wall-plant. 



D. amabills (lovely). A synonym 



of D. grandiflora. 

 D. canadensls (Canadian). A .<y. 



nonym of D. trifida. 

 D. floritranda (many-flowered), ft., 



corollas purplish, narrow, tubular, 



only slightly expanded towards the 



mouth. June. A. 3ft. Japan, 1864. 



SYN. D. multiflora. (I. H. 383.) 

 D. grandiflora (large-flowered).* 



fl. pink. Early summer. I. strongly 



reticulated, the veins being very 



prominent on the under side. A. 



8ft. Japan. SYN. D. amabilis. 



(F. d. S. 855.) There are several 



very ornamental varieties : Isolmat, 



flowers white, with a yellow blotcli 



in the throat (F. d. S. 1446) ; striata, 



striped red and white (F. d. S. 



1446) : and Van Houttei, white and 



rose, very showy (F. d. S. 1447) ; 



another variety, variegata, has 



prettily variegated leaves (F. d. S. 



1189). FIG. 666. DIERVILLA 



D. hortensis (garden). /. red or ROSEA. 



white ; corolla tube slender, slightly 



hairy outside, glabrous within ; limb regular, with spreading ovate 



lobes. I. stalked, ovate, acuminate, crenate, or crenate-serrulate, 



softly hairy, h. 4ft. to 5ft Japan. (S. Z. F. J. 29.) 

 D. Middendorflana (Middendorf s). /. yellowish-white, dotted 



with pink on the lower petal ; panicles terminal. I. nearly sessile, 



ovate-lanceolate, finely reticulated, hairy on the nerves. Sibena. 

 D. multiflora' (many-flowered). A synonym of D. floribunda. 

 D. rosea (rose).* fi. rosy or white, very numerously produced. 



Spring. I. ovate-lanceolate, serrulate, h. 6ft. China, 1844. See 



Fig 606. Of this widely-grown species, there are several excellent 



varieties : nana is a very compact, dwarf-growing form : nana 



aurea is like nana, except that the foliage (particularly ma voun^ 



state) is a rich golden colour ; Stel&ifri is ;i vory floriferous 



purplish-red form. 



Diervilla continued. 



D. tiifida (trifid). fl. yellow. Summer. I. on short petioles, 

 ovate, acuminated, serrated, and, as well as the petioles, glabrous. 

 Root creeping, h. 3ft to 4ft North America, 1739. SYN. 

 D. canadentis. 



DIFFUSE. Scattered ; widely spread. 



DIGGING. For pulverisation and mixing-in of 

 manures, Digging is best performed (says London) in dry 

 weather ; but, for the purpose of aeration, a degree of 

 moisture and tenacity in the soil is more favourable. In 

 Digging, a uniform depth should be preserved throughout, 

 the full length of the spade being inserted nearly vertically, 

 and the spit turned over, so that what was before under- 

 neath may now be exposed to the air. An open trench, 

 the length of the ground to be dug, should first be made, 

 and the soil thus removed transferred to the place where 

 it is intended to finish. In order to leave the surface, 

 when completed, evenly disposed, the trench must be kept 

 tolerably straight, and of about an even width. Ground 

 that has been occupied by garden crops in summer, is best 

 thoroughly dug in the autumn, and manure added. It 

 should not be broken by the spade, but left rough for 

 full exposure to the frost, and for the consequent aeration 

 in winter. The following spring, such soil will be found 

 to work well, and may be prepared, by levelling down, for 

 any desired crop. The strength of the manure will also 

 have become incorporated with the soil underneath a 

 condition that cannot be obtained by adding it at planting 

 time. The width of ground taken as a spit must not 

 exceed about 9in. in heavy soils, or the bottom will be 

 left undisturbed. Digging is best performed when the 

 soil is somewhat dry, and should never be practised when 

 it is frozen or covered with snow. Light soils, or those 

 resting on a gravelly bottom, may be worked at many 

 times when it would be very unwise to tread on those of 

 a clayey nature. The workman, when Digging, should 

 stand nearly erect, insert the spade vertically, to secure 

 the removal of soil to the full depth, and turn the spit 

 from the direction in which he is standing. If a com- 

 petent man, he will be able to reverse the position of his 

 hands on the spade, and proceed either way with equal 

 facility. 



Double-digging is performed by having a trench of 

 double width, removing a spit of the earth on the top, 

 then Digging underneath, and allowing that portion to 

 remain. Another width is then marked out, the top soil 

 from this placed on the other, and each portion treated 

 successively in a similar manner. This method is often 

 adopted where sub-soils are poor, so that the depth of 

 two spits may be reached, without introducing the in- 

 ferior soil to the surface. 



DIGITALIS (from digitus, a finger ; referring to the 

 shape of the flowers). Foxglove. OBD. Scrophularineae. 

 A genus of eighteen species of very showy hardy biennial 

 or perennial herbs, confined to Europe, North Africa, and 

 West Asia. Flowers purple, yellowish, or white, disposed 

 in long terminal, sometimes secund, racemes; corolla tu- 

 bular at the base, funnel-shaped ; limb obliquely four-lobed ; 

 upper segment much shorter than the lower one or lip, and, 

 as well as that, imbricate in aestivation. The culture of 

 this genus is very simple ; the plants thriving in any 

 ordinary garden soil. Seeds should be sown in April or 

 May, and the seedlings, when large enough to handle, 

 may be planted out Gin. apart. Also increased by divi- 

 sions. 

 D. amblKna (ambiguous).* fl. yellowish, reticulated with brown, 



large, 2m. long ; lower bracts about equal in length to the 



flowers. July, August. I. ovate-lanceolate, toothed, sessile, 



nerved, downy beneath, h. 2ft. to 3ft. Europe, 1596. Perennial. 



Plant hairy. SYNS. D. yrandiflora and D. ochroleuca. (B. R 



64.) 

 D. a. fnscescens (dark brown). A variety with brown flowers, 



which are smaller than those of the type. 

 D. aurea (golden). A synonym of D. ferrwjinea. 

 D. dnbia (doubtful), fl., corolla purplish, large for the size of the 



plant, marked by many spots fiaride ; throat dilated ; racemes 



