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, in allusion to the anthers having double the usual number of cells). Araliaceae. Graceful hothouse plants, grown practically exclusively for foliage; usually known as Aralia.
Usually shrubs, sometimes small trees, entirely unarmed, and differing in this from some hardy aralias: leaves always digitate, of 5-9 leaflets, varying much in adult and juvenile characters, sometimes slender and threadlike, again broad and leathery, usually long-stalked: calyx and corolla 5-parted; stamens 5, with thick anthers; ovary 10-celled; styles 10. All these flower-characters are drawn from wild plants, as the cult, specimens are not known to flower. - Only 3 or 4 species are known in the wild state, all from the tropical isls. of the Pacific. The many names in horticultural literature are probably referable, ultimately, to some of these species, but their true position will be settled only when they flower. Here must be sought all the digitate-lvd. tender aralias of the first edition of this cyclopedia, the pin-nate-lvd. species going toPolyscias. R.H. 1912, p. 491.
Dizygothecas require light rich soil, made up of equal parts of sandy loam and peat or leaf-mold. They require plenty of water and a moist warm atmosphere. Scale pests are numerous and must be kept down by frequent sponging with weak solutions of whale-oil soap, fir-tree oil or other insecticide.
The names here used are retained in the absence of specific information as to what wild species of Dizy-gotheca they are to be associated with. Only complete flowering material can settle this much-vexed question. All of the following are distinct horticulturally.
Kerchoveana, Hort. Leaves the shape of a Ricinus, the 7-11 lfts, elliptic-lanceolate or oblong-lanceolate, with undulate and serrate margins and a pale midrib. S. Sea Isls. Certificated in England in 1881 (Gn. 19, p. 457). R.H. 1891, p. 225. - Slender-stemmed, of beautiful habit. According to Harms, perhaps better put in Pseudopanax.
Veitchii, Hort. leaflets 9-11, very narrow or almost filiform, undulate, shining green above and red beneath. New Caledonia. - -One of the best and handsomest species. variety gracfllima, Hort. (Aralia gracillna, Lind.). Lfts, still narrower, with a white rib. R.H. 1891, p. 226. Gn. 39, p. 565. I.H. 22:225. - Very desirable. Originally described as Aralia gracilina (thin-lined), which name has been mistaken for gracillima (very graceful).
Veitch. Petioles mottled with white; leaflets 7-11, filiform and pendulous. New Hebrides. G.Z. 21, p. 28. - Excellent. Thought by Guillemin to be the juvenile form of some Dizygotheca. Many of the greenhouse aralias have a permanent juvenile condition.
Hort. Slender plant: lfts, filiform and drooping, broadened at the extremities, deep green. Australasia.
Reginaae, Hemsl. (Aralia regina, Hort.). Graceful: petioles olive, pink and brown; lfts, drooping, very narrow, not undulate. New Hebrides. I.H. 26:337.
The following greenhouse aralias, with showy leaves, probably belong to Dizygotheca, unless otherwise noted:
A. Chabrieri, Hort. See Polyscias. - D. crassifolia, Soland. See Pseudopanax. - D. longipes, Hort. Leaves digitate, the leaflets oblong-lanceolate, acuminate, wavy. N. Austral. - D. nobilis, Hort. "A theophrasta-like plant, with closely packed, bold foliage, the leaves oblong obovate-acuminate, undulate at the margins." Not certainly referable to Dizygotheca. - D. Osyana, Hort. Like A. leptophylla, but lfts, deeply bifid, and nerves and veins brown. S. Sea Isls. - D. quercifolia, Hort. leaflets 3, sinuate: leaves opposite. New Britain. Perhaps not of the Araliaceae. The plant has opposite leaves - D. rotunda, Hort. leaf of a single orbicular-cordate 1ft. or sometimes 3-foliolate, white-toothed. Polynesia. Not certainly referable to Dizygotheca. - D. spectabilis, Hort.=? - D. splendidis-sima, Hort. Leaves pinnate, the lfts, shiny green. New CaIedonia= Polyscias. - D. terndta, Hort. Leaves opposite, ternate, or 3-lobed, the lfts, oblong-lanceolate and sinuate. Not certainly referable to Dizygotheca. - D. Victoriae, Hort.=Polyscias. at TayLor