AN ENCYCLOPEDIA OF HORTICULTURE. 



497 



ONOCLEA (changed from the Greek name of a plant, 

 Onokleion, or from twos, a vessel, and kleio, to close ; 

 alluding to the singularly rolled-tip fructification). In- 

 cluding Struthiopteris. OED. Filices. A small genus 

 (three species) of hardy Ferns, inhabiting cold and tem- 

 perate regions. Sori dorsal, globose, on the veins of the 

 changed and contracted pinnae of the fertile fronds, and 

 quite concealed by their revolute margins; involucre 

 very thin, delicate-membranous, hemispherical or half 

 cup-shaped, originating from the inferior side of the 

 sorus, or wanting. The species thrive 

 best in a good, strong, loamy soil, and 

 are very suitable for the outdoor 

 fernery. For general culture, see 

 Ferns. 



O. germanica (German).* Ostrich Fern. 



fronds broad-lanceolate, long-attenuated 



at the base ; fertile pinnae short, much 



contracted, linear-terete, torulose, lobed 



and torn at the margin; involucre cup- 



shaped, very fragile, and soon obso- 



lete. Northern hemisphere. A hand- 



some species. SYNS. Struthiopteris ger- 



manica, S. pennsylvanica. 

 O. orientalis (Eastern), fronds ovate- 



oblong, not attenuated at the base ; 



fertile ones oblong, often 2ft. long, con- 



tracted ; pinn;e linear-oblong, flattened, 



two-edged, the broad, refracted margins 



covering the whole back, dark purple- 



brown, glossy, at length spreading, torn 



at the margin. Sikkim, Japan. SYN. 



Struthiopteris orientalis. 

 O. sensibilis (sensitive).* Rootstock ex- 



tensively creeping, fertile fronds bipin- 



nate ; pinnules recurvate, globose, sterile 



fronds rising separately from the naked 



rootstock, long-stalked, broadly triangular 



in outline, deeply pinnatifid into lanceo- 



lateo-blong pinnae, which are entire or 



wavy-toothed ; involucre a globose pel- 



licle, bursting at the summit. North 



America, North Asia, 1799. 



O. s. obtusilobata (obtuse-lobed). A 



rare abnormal form, in which the pinnae 



of some of the sterile fronds, becoming 



again pinnatifid, and more or less con- 



tracted, bear some fruit-dots without 



being much revolute, or losing their foliaceous character. Penn- 



sylvania. 



ONONIS (the old Greek name used by Theophrastus). 

 Rest Harrow. ORD. Leguminosce. An extensive genus 

 (about sixty species) of glabrons, pubescent, or villous, 

 greenhouse or hardy, annual, biennial, or perennial herbs, 

 sub-shrubs, or rarely shrubs, inhabiting Europe, Western 

 Asia, and North Africa, and extending to the Canary 

 Islands. In the British Flora, the genus is represented 

 by the variable 0. spinosa, an under-shrnb, and 0. re- 

 clinata, a low-growing annual. Flowers pink, yellow, or 

 white, in axillary, solitary, or two or three-flowered, 

 racemose peduncles, or sessile. Pod oblong or linear, 

 two-valved. Leaves usually pinnately trifoliolate ; stipules 

 adnate to the petioles. Several species are of easy cul- 

 ture in any ordinary garden soil, and are very suitable 

 subjects for growing on banks and rockwork. Propa- 

 gated by seeds, or by divisions. The species here de- 

 scribed are those best known to cultivation. 



O. arragqnensis (Arragon).* fl. yellow, almost sessile, twin, 



disposed in a leafless raceme ; calyx half as long as the corolla. 



May to July. I. trifoliolate, clabrous ; leaflets roundish, serrated. 



h. 1ft. to 2ft. Spain, Arragon, &c., 1816. Half-hardy shrub. 

 O. fruticosa (shrubby), fl. purple ; peduncles three-flowered, 



disposed in a raceme. Summer. I. trifoliolate ; leaflets sessile, 



smooth, lanceolate, shining, unequally serrated, h. 1ft. to 2ft. 



South-western Europe, 1680. A handsome, low-growing, hardy 



shrub. (B. M. 317.) 



Ononis continued. 



O. Natrix (goat-root).* /. yellow, veined with red ; pedicels one- 

 flowered, each furnished with an awn. Summer I. alternate 

 trifoliolate ; leaflets oblong, serrated at the apex, the upper 

 ones sometimes simple, h. lift, to 2ft. South Europe 1683. 

 Hh * dammy P ubes>cence - 



O. pednncularis (peduncular). /., petals white, with pink 

 margins; peduncles thrice as long as the leaves, slender, glan- 

 dular-pubescent. April. I. simple, obovare, dentate, pubescent 

 patent or recurved, h. Ift Teneriffe, 1829. Tender perennial 

 aero. (r>. t. 144 1.) 



O. hispanica (Spanish), fl. yellow ; pedicels one-flowered. July. 



1. trifoliolate ; leaflets nearly rou 

 pubescent; stipules spreading, 

 Half-hardy shrub. (B. M. 2450.) 



arly round, undulate, toothed, clammy 

 pubescent ; stipules spreading, deflexed. h. IJft. Spain, 1799. | 



O. minutissima (very small). fl. yellow, in leafy, ag 

 spikes ; corolla shorter than the calyx. June. I. trifoliolate ; 

 leaflets oblong, obovate-cuneate, serrated ; stipules subulate, 

 entire, h. Sin. South-west Europe, 1818. A somewhat tufted 

 hardy biennial. (J. F. A. 240.) 



Vol. TI 



FIG. 744. OXONIS ROTUNDIFOLIA, showing Habit and detached 

 Single Flower. 



O. rotundifolia (round-leaved).* fl. rose; peduncles three 

 flowered, bractless. Summer. 1. trifoliolate ; leaflets obovate, 

 roundish, toothed, h. 1ft. to lift. South Europe, 1570. A very 

 handsome and most desirable, somewhat shrubby, hardy species. 

 See Fig. 744. (B. M. 335.) 



O. viscosa (clammy), fl. yellow, the back of the standard striped 

 with purple, numerously disposed in panicled spikes. Summer. 

 1., lower ones trifoliolate, upper ones simple, h. IJft. to 3ft. 

 South Europe, 1759. A handsome, hardy annual. (S. F. G. 678.) 



ONOPORDON (the old Greek name, said by Pliny 

 to be derived from CMOS, an ass, and pordon, crepitus ; 

 on account of its effect upon the asses who eat it). 

 Sometimes spelt Onopordum. Cotton Thistle. OED. 

 Composite. A genus comprising about a dozen speojies 

 of hardy annual, biennial, or perennial herbs, sometimes 

 tall and branched, with decurrent, winged stems, some- 

 times almost stemless. They axe natives of Europe, 

 North Africa, and Western Asia. Flower-heads purplish, 

 violet, or white, large ; involucre globose or broad ; re- 

 ceptacle flat, fleshy; achenes glabrous. Leaves radical 

 or alternate, pinnatifid or sinuate-toothed. Two or 

 three species of this genus are grown for their stately 

 habit, and large and showy flowers. They will generally 

 thrive in almost any ordinary garden soil, and are more 

 especially adapted for the rougher parts of the sub- 

 tropical garden. Seeds should be sown, in moderately 

 good and well-drained soil, in early spring. 

 O. Acanthium (Acanthium).* Common Cotton Thistle, fl.-heads 

 purple, large ; scales of the calyx subulate, spreading in every 

 direction. July. I. oblong, inclining to ovate, woolly on both 

 sides. Stem branched, woolly, h. 4ft. to 5ft. Europe (Britain), 

 Siberia. A very handsome perennial, with a bold habit and 

 vigorous growth. (F. D. 909 ; Sy. En. B. 680.) 

 O. arabicum (Arabian), fl.-heads purple. 'I. having both sides 

 covered with a white down. Stem also woolly, slightly branch- 

 ing, erect, h. 8ft. South Europe, 1686. Biennial. (B. M. 



