DEACOCEPHALUM 



broadly heart-shaped, and all Ivs. pubescent beneath in- 

 stead of nearly glabrous: fls. purplish to deep purple. 

 June, July. Himalayas. B.M. C281. 



B. Whorls distant, in long racemes. 

 C. Flowers erect. 



Moldivioa, Linn. Lvs. lanceolate, inciso-crenate, the 

 floral ones narrower and saw-toothed at the base. Eu., 

 N. Asia. 



Riiprechtii, Regel. Lvs. ovate-lanceolate, variously 

 incised and toothed: fls. rosy purple or lilac, about 1 in. 

 long, in axillary clusters. Turkestan. Gt. 1018. 

 cc. Fls. somewhat nodding. 



niitans, Linn. Lvs. ovate, crenate, the floral ones ob- 

 long-lanceolate and more nearly entire : fls. blue. May- 

 July. N.Asia. Mn. 4:137. B.R. 10:841. -Var. alplna, 

 Hort., is commoner. 



D. Tirginidintin, Linn. See Physostegia.— i). Canadense of 

 Bridgeman's Catalogue is a misprint for D. Cauariense=Ce- 

 droneUa triphyUa. j. g. Keller and W. M. 



DBACONCUITTS (Latin, a little dragon). Ar&cem. 

 This genus contains the plant pictured in Fig. 734. It 

 has uncanny, draarou-tin^ered Ivs. and a terrifying odor 

 when in flower. Its tulji-rs are sold by bulb dealers un- 

 der the name of ^»-Hm DraruinKlii.s. The latest monog- 

 rapher of this order (Engler, in DC. Jlon. Phan., vol. 

 2, 1879) puts this plant into the genus Dracunculus be- 

 cause the ovules are attached to the base of the ovary, 

 while in Arum they are attached to the side. The lvs. 

 of the true Arums are always arrow-shaped, while in Dra- 

 cunculus they are sometimes cut iuto finger-like lobes. 

 For culture, see Arum. 



There are only 2 species. The common one is an en- 

 tertaining, not to say exciting, plant. When it flowered 

 in the forcing-houses at Cornell University, innocent 

 visitors thought there must be a dead rat under the floor. 

 It is well worth growing for the experience, though its 

 stench is not quite as bad as that of a Helicosideros, 

 sold as Arum crinifum, which makes any house un- 

 bearable in which it flowers. Nearly all Arums are ill- 

 smelling. 



vulgaris, Schott. Fig. 734. Sheath of lvs. livid, spot- 

 ted : stalks green : blades with 10 fingers projecting 

 from a bow-shaped base : tube of spathe streaked with 

 purple except at the bottom: spathe purple all over and 

 much darker along the wavy border. Mediterranean 

 regions. ^. H. 



DEAGON PLANTS. The Dragon Arum, Dragon Root 

 or Green Dragon, is the native Ariscsma Dracontiitm. 

 The Dragon Plant of Europe is Dracunculus vulgaris. 

 The Dragon's Head is not an Aroid, but a Dracocepha- 

 lum, a genus of mints. False Dragon's Head is Physo- 

 stegia. The Dragon's Blood of commerce is a dark red, 



DRAINAGE 505 



astringent, resinous secretion of the fruits of a palm, 

 Damonorops Draco. Other kinds of Dragon's Blood 

 are produced by Dracwna Draco and Eeastaphyllum 

 Monetaria. "Sticks," "reeds," "tears" and "lumps" of 

 Dragon's Blood are known to commerce. The resin is 

 used in coloring varnishes, dyeing horn in imitation of 

 tortoise shell, and n the composition of tooth-powders 

 and various 



DBAINA6E. Underground or sub-drains serve to re- 

 lieve the land of free water, which is harmful to most 

 plants if left to stagnate in the surface soil or subsoil. 

 They serve not only to dry the land in early spring, but in- 

 directly to warm it, for if the water is removed the sun's 

 heat warms the soil instead of cooling it by evaporating 



m^ 



the surplus water. Tenacious lands devoted to garden- 

 ing and small fruits are made more productive, warmer 

 and earlier by sub-drainage. Drains promote nitrifica- 

 tion, assist in liberating mineral plant-food and cheapen 

 tillage. They serve not only to remove deleterious stag- 

 nant water, but they promote aeration as well, and this 

 hastens beneficial chemical changes in the soil. Drainage 

 promotes the vigor, healthfulness and fruitfulness of 

 plants. Tenacious soils are m; 

 thereby giving easier access 

 percolation through the soil r 

 some plant-food, is hastened, 

 is warmer than the soil; in ni: 

 the soil: therefore, percolatio 

 soil in the spring and cools it 

 Drains serve not only to relie 

 they impart to it power to hold additional available mois- 

 ture, which materially benefits plants during droughts. 

 Drainage is of two kinds, surface and sub-drainage. 

 On land on which large outlays of money are to be ex- 



• fri.ililp by drains, 

 ph.nt r..Mt., while the 

 ■aiuuai.T, w hii-b carries 

 v;nii\\;iicr in the spring 

 uiiiiiiir it is cooler than 

 >f rainwater warms the 

 extremely hot weather, 

 land of free water, but 



pended, as in horticultural pla 

 utmost importnncp that the soil li 

 depths from stairnant water. Tr 



3 of the 

 siderable 

 ■ubs, and 

 • into the 



subsoil than iii"-t nf th 

 greater deptli of .Irainc-i 

 ture the planting may of 

 10 years, while with nia 

 lows the plantintr in a ft 

 loses one crop, an annti; 

 loss is not great, but if tl 

 of labor by planting oi 



req 



lire I 



^ T Mnj the effect of lowering the ' 

 of under-draining 

 On the undramed soil the roots do not penetrite 

 droughts comj the plant': suffer 



horticul- 

 n i.recidc tin- harvest by 5 to 

 ■ farm crops the harvest fol- 

 nionths. If the grain raiser 

 by ]>laiiting on wet land, the 

 or'chardist loses 15 to 20 years 

 undrained lands, before the 

 iscovered, the losses are seri- 

 ous. Some lands require little more than 

 to be relieved from surplus surface water 

 in early spring. This may be accomplished 

 by forming ridges and open furrows as 

 far asunder as the rows of trees are to be 

 placed. But it is only rarely that surface 

 drainage fully prevents serious damage 

 from surplus moisture. Surface drainage 

 may be considered a cheap way of tem- 

 porarily alleviating undesirable condi- 

 tions. It does not always eradicate them. 

 Fig. 735 illustrates how sub-drainage low- 

 ers the water-table (or the area of stand- 

 ing water), and thereby ameliorates the 



Sub-drainage consists in placing con- 

 duits of tile or other material in the 

 ground at depths varying from 2^-4 feet, 

 and at such distances apart as will serve to 

 relieve the subsoil of deleterious stagnant 

 water. When suitable stones are at hand 

 they are sometimes used instead of tile 

 for forming drainage conduits. If such 

 use is made of them, the drains should be 

 somewhat deeper than tile drains, since 

 the stones which form the drain occupy 



