This section is from the book "The Standard Cyclopedia Of Horticulture Vol2", by L. H. Bailey. See also: Western Garden Book: More than 8,000 Plants - The Right Plants for Your Climate - Tips from Western Garden Experts.
(Greek, dragon's head, from the shape of the corolla). Labidtae. Hardy herbaceous annual and perennial plants of easy culture and of minor importance.
Allied to Nepeta, differing in having the calyx mostly straight rather than curved and unequally toothed: mostly erect herbs, with opposite entire, toothed or deeply cut leaves, the upper ones passing into bracts: flowers in many-flowered verticils which are axillary or terminal, blue or purple or rarely white; calyx tubular, about 15-nerved; corolla, upper lip somewhat notched and arched, the lower one 3-cleft and the middle part notched or 2-cleft; stamens 4, didynamous, the 2 anther-cells divaricate. - Forty species in Eu. and Asia and very sparingly in N. Amer.
Sandy loam, moderately rich, and a rather moist, partially shaded situation will suit these plants best. In a sunny dry border they are never very showy; the flowers are of short duration, and are seldom at their best except in very moist seasons. Propagation is by division or seeds. The species described below are erect-growing.
a. Leaves entire, not cut in any way.
Ruyschiana, Linn. (Ruyschiana spicdta, Mill.). Perennial, 2 ft.: stems slightly pubescent: leaves linear-lanceolate, glabrous: bracts ovate-lanceolate, entire: whorls in somewhat interrupted spikes; flowers 1 in. long, purplish blue or purple; anthers villous. Siberia. variety japonicum, Hort., has white flowers shaded with blue, and is a distinct improvement. G.C. II. 12:167. - According to Vilmorin, this species has been sold as D. altaiense (see D. grandiflorum).
aa. Leaves deeply 3-5-cleft. austriacum, Linn., has the habit of the above, and belongs to the same subgenus Ruyschiana, but the leaves are divided and more distinctly revolute at the margin. About 1-1 1/2 ft. high: flowers blue, 1 1/2 in. long and more: perennial. July, Aug. Eu., Caucasus.
aaa. Leaves cut only at the margin; mostly crenate.
B. Whorls crowded together into spikes or heads.
Linn. (D. altaiense, Laxm.). Perennial, about 1 ft. high: root-leaves long-stalked, oblong, notches at base; stem - leaves few, short-stalked, ovate, not notched at base, the uppermost still more rounded: whorls in spikes 2-3 in. long, the lowest whorl usually at some distance: flowers 2 in. long, blue. June, July. Siberia. B.M. 1009. P.M. 13:51.
Benth. Allied to D. grandiflorum, but stem pubescent instead of pilose above: root-leaves more broadly heart-shaped, and all leaves pubescent beneath instead of nearly glabrous, and wrinkled: flowers purplish to deep purple. June, July. Himalayas. B.M. 6281.
bb. Whorls distant, in long racemes.
Moldavica, Linn. (Moldavica punctata, Moench). Leaves lanceolate, inciso - crenate, the floral ones narrower and pectinate: flowers in few-fid. loose clusters; corolla 2 or 3 times as long as calyx, blue or white. European annual, 1-2 ft., sparingly run wild in N. Amer. Eu., N. Asia.
Ruprechtii, Regel. Perennial: dwarf or compact, 1-1 1/2 ft.: leaves ovate-lanceolate, incised and toothed: flowers rosy purple or lilac, about 1 in. long, in axillary clusters. Turkestan. Gt. 1018.
Linn. Perennial, 1 ft.: leaves ovate-crenate, the floral ones oblong-lanceolate and more nearly entire: flowers blue. May-July. N. Asia. Mn. 4:137. B.R. 841. variety alpina, Hort., is advertised.
D. canariense=Cedronella triphylla. - D. caniscens, Linn.= Lallemantia. - D. virginidnum, Linn.=Physostegia.
Wilhelm Miller. L. H. B.†