AN ENCYCLOPAEDIA OF HORTICULTURE. 



527 



ORNITHOPTJS (from ornis, ornithos, a bird, and 

 pous, a foot; referring to the claw-like legumes or seed- 

 pods). Bird's Foot. Including Astrolobium. OED. Legu- 

 minosce. A genus comprising about seven species of 

 small, low-growing, hardy annuals. Flowers small, pink, | 

 white, or yellow, in long peduncled heads or umbels. 

 Leaves impari-pinnate. None of the species are worth 

 growing for horticultural purposes. The genus is repre- 

 sented in the British Flora by 0. ebracteatus (from Scilly 

 and the Channel Islands), with bright yellow flowers, 

 veined with red, and 0. perpusillus, a widely- distributed 

 species, with white, red-veined flowers. 



ORNITHOXANTHUM. A synonym of Gagea. 



ORNITROFHE. A synonym of Schmidelia 



(which see). 



ORNUS. Included nnder Fraxinns (which see). 



OROBANCHACEJE. An order of leafless, parasitic 

 herbs, of various colours (never green), for the most 

 part natives of Europe, North Africa, and extra-tropical 

 Asia and North America, a few being found between 

 the tropics in Asia, Africa, or mountainous or extra- 

 tropical South America, and one in Europe and South 

 Australia. Flowers hermaphrodite, regular, solitary in 

 the axils of the bracts, sessile or pedunculate, few, or 

 in dense, terminal, crowded spikes ; calyx four or five- 

 toothed or lobed ; corolla lobes five, often broad, imbri- 

 cated ; stamens four, didynamons, inserted on the 

 corolla tube. Scales alternate, densely crowded or 

 scattered, upper ones bract-like. Stems or scapes erect, 

 short or elongated, simple or slightly branched. Some 

 of the species are agricultural pests, and do great 

 damage, e.g., Orobanclie pruinosa, on Beans ; 0. cruenta, 

 on Saintfoin ; 0. minor, on Clover ; O. rubens, on Lucerne ; 

 Phelipcea ramosa, on Maize, Tobacco, and Hemp. The 

 order comprises eleven genera (the best known being 

 Orobanche) and about 150 species. 



OROBANCHE (the old Greek name used by Dios- 



corides, and said to be derived from Orobos, Vetch, and 

 ancho, to strangle, because the species were supposed to 

 kill the plants on which they grow). Broom Eape. 

 OED. Orobanchacece. A very large genus (above 150 

 species have been described, but the number of those 

 entitled to specific rank may be reduced to about 100, 

 or less) of various-coloured plants, broadly dispersed 

 over the Northern temperate regions of the Old World, 

 rarely found in the tropics or the Southern hemisphere, 

 and scarcely ever in America; six are natives of Britain. 

 Flowers at the axils of the scales, sessile or sub-sessile, 

 bibracteolate or ebracteolate, densely or interruptedly 

 spicate. Scales often acute. The species have no horti- 

 cultural value. They are, however, decidedly interesting 

 plants ; the annual species may be sown together with 

 the seeds of the host plants they particularly affect. 

 Those of perennial duration should be sown near their 

 special host plants ; as, however, three years elapse 

 before the young parasites arrive at the flowering stage, 

 it is better to fence off the places where they are sown, 

 and not disturb the ground. 



OROBELLA. Included under Vicia (which see). 



OROBUS (the old Greek name used by Theo- 

 phrastus ; it has nothing to do with the present 

 genus). Bitter Vetch. OED. Leguminosae. An exten- 

 sive genus of usually hardy, herbaceous perennials, 

 mostly natives of the Northern hemisphere, and ' now 

 included (by Bentham and Hooker) as a section of 

 Lathyrus, from which it differs in having no tendril at 

 the tip of the petiole. For horticultural purposes, how- 

 ever, the two genera are here kept distinct. Many 

 species are very handsome ; they thrive in almost any 

 soil, and are readily increased by dividing the tufted 

 rootstocks in spring. Some force readily, and make 



Orobus continued. 



charming pot plants for cool-house decoration. The 

 species here described are those generally found in 

 gardens. 



O. atropurpureus (dark-purple). A synonym of Vicia sicula. 

 O. aurantius (orange-coloured).* A. deep yellow ; peduncles 



elongated, shorter than the leaves. June. I. with five or six 



n" 's of lanceolate, bluntish leaflets. Steins simple, angular. 

 4ft. Caucasus, 1818. (S. B. F. G. ser. ii. 198.) 



O. canescens (canescent). A synonym of O. fdtformig. 



O. filifonnis (thread-formed), fi. white, with a tinge of blue ; 

 peduncles many-flowered, longer than the leaves. May. I. with 

 usually two or three pairs of linear, bluntish, pubescent or 

 dotted leaflets. Stem tetragonal, h. lft. South Europe, 1816. 

 SYN. 0. canescens. (B. M. 3117.) 



O. Fischer! (Fischer's). A synonym of Vicia sicula. 



O. flaccidus (flaccid).* ft. purple ; vexillum with two prominent 

 obtuse teeth near the middle, which embrace the inner petals ; 

 peduncles terminal or axillary. May. I. remote, spreading, of 

 two or three pairs of opposite, very long, linear, attenuated, 

 glabrous leaflets, dark green above, paler beneath; stipules 

 large, semi-sagittate. Stem erect, h. 6ft. Croatia, &c. (B. M. 

 2937, under name of 0. stipulaceus, and wrongly ascribed to 

 North America.) 



O. hirsutus (hairy), fl. red ; racemes axillary, twice as long as 

 the leaves, few-flowered. May. I. ovate, acute, with parallel 

 nerves, h. 1ft Thrace, <fcc., 1822. (B. M. 23*5 ; S. B. F. G. 

 ser. ii. 302.) 



O. lutens (yellow), fl. yellow ; peduncles elongated, many- 

 flowered, about equal in length to the leaves. June. I. with 

 three to flve pairs of elliptic-lanceolate, mucronulate leaflets, 

 which are glaucous beneath. Stems simple, angular, h. 1ft. to 

 2ft. Europe, 1759. (L. B. C. 783; S. B. F. G. ser. ii. 115.) 



O. niger (black), fl. purple; peduncles many-flowered, longer 

 than the leaves. June. 1., leaflets elliptic, mucronulate, with 

 almost parallel nerves, h. 3ft. Europe (Britain). (B. M. 2261 ; 

 Sy. En. B. 407.) 



O. pannonicus (Hungarian).* jt. very variable in colour, ranging 

 from white and cream tinged with rose, to purple and white and 

 yellow ; peduncles many-flowered, longer than the leaves. May. 

 I. with two or three pairs of linear, mucronate leaflets. Stem 

 simple, h. 1ft. South Europe, 1794. (J. F. A. 39 ; S. B. F. G. 22.) 



O. p. varius (various-flowered). /. with the standard rose- 

 coloured, and the keel and wings yellowish ; peduncles many- 

 flowered, longer than the leaves. May. 1. with three or four 

 pairs of linear-lanceolate, mucronulate leaflets. Stems simple, 

 angular, h. IJft Italy, 1759. (B. M. 675.) 



O. sessilifoliiis (stalkless-leaved). fl. purple, in few-flowered 

 racemes. May. I., leaflets narrow, dark green, almost sessile. 

 h. 1ft. Greece, &c., 1823. (B. M. 2796; S. F. G. 692.) 



O. variegatus (variegated). fl. finely variegated, small. Early 

 summer. I. with two or three pairs of lanceolate leaflets. Stems 

 simple, flexuous. h. 1ft. Europe, 1821. (S. B. F. G. ser. ii. 28.) 



O. vernus (spring).* fl. purple and blue, with red veins, the keel 

 tinted with green, the whole changing to blue, secund, nodding ; 

 peduncles axillary, many-flowered, shorter than the leaves. 

 Spring. I. with two or three pairs of ovate-lanceolate, acuminate, 

 shining leaflets. Stems simple, flexuous. h. 1ft. Europe, 1629. 

 (B. M. 521; S. F. G. 691.) 



ORONTIE2E. A tribe of Aroideae (Aracece). 



ORONTIUM (the old Greek name for a plant said 



to grow on the banks of the river Orontes). OED. Aroidece 



(Aracece). A monotypic genus, the species being a hardy 



aquatic perennial, with a deep rootstock. This should 



be planted in open water, from 6in. to 12in. beneath 



the surface. Propagated by divisions. 



O. aqnatlcum (aquatic), fl. perfect, crowded all over the narrow 



spadix which terminates the elongated scape ; lower ones with 



six concave sepals and six stamens, upper ones with four ; spathe 



incomplete and distant. May. ir. a green utricle. I. entire, 



oblong, nerved, long-petioled. North America. (H. E. F. 19 ; 



L. B. C. 402.) 



OROFHOMA. Included nnder Mauritia (which 



see). 



OROTHAMNUS. Included under Mimetes (which 



see). 



OROXYLUM (from ores, a mountain, and xylon, 

 wood; referring to the habitat). OED. BignoniacecB. A 

 monotypic genus, the species being a glabrous stove 

 tree, which requires almost unlimited root space for its 

 successful cultivation; it does best when planted out in 

 a well-drained, prepared border of turfy loam, leaf mould, 

 and sand, and the long shoots trained near the glass. 



