AN ENCYCLOPEDIA OF HORTICULTURE. 



203 



Isotoma continued. 



Z. longlflora (long-flowered), fl. white ; tube of corolla very long 

 and slender. Summer. I. obovate-lanceolate, coarsely toothed, 

 pubescent. West Indies, 1752. Greenhouse perennial. A very 

 poisonous plant. (B. B. 1200, under name of Lobelia longiflora.) 



Z. senecioides subpinnatifida (Sececio-like, sub-pinnatifid). 

 A synonym of /. axillaris subpinnatiflda. 



ISOTROFIS (from isos, equal, and tropis, a keel; 

 in reference to the shape of the carina). OBD. Legu- 

 minosce. A genus of eight species of greenhouse herbs 

 or under - shrubs, with diffuse or ascending stems. 

 Flowers solitary, on axillary peduncles, or forming a 

 loose terminal raceme. Leaves alternate, simple or uni- 

 foliolate, with linear-falcate or minute stipules. The 

 species are all Australian. I. striata, perhaps the only 

 one in cultivation, requires treatment similar to Chori- 

 zenxa (which see). 



Z. striata (striated), fl., standard yellow with purple streaks, 

 large ; wings and keel purple. Spring. I. not numerous ; lower 

 ones obovate or cuneate, very obtuse, truncate or broadly two- 

 lobed ; upper ones narrower, and sometimes acute. Some branches 

 quite leafless and dichotomous. A. 6in. to 18in. A hairy perennial 

 or under-shrub. SYN. Chorizema spartioides (under which name it 

 is figured in L. B. C. 1953). 



ITEA (from Itea, the Greek name of the Willow, as far 

 back as Homer ; applied to this genus on account of the 

 quick growth of the species named below). OBD. Saxi- 

 fragece. A genus comprising about five species of trees 

 and shrubs, natives of North-west America, Japan, China, 

 Java, the Himalayan Mountains, and Khasia. Flowers 

 white, small. Leaves alternate, petiolate, oblong or 

 lanceolate, glandulose-dentate or crenate. The only re- 

 presentative of this genus yet introduced is I. virginica, 

 an ornamental hardy deciduous shrub, which, when in a 

 vigorous condition, during autumn, is entirely covered with 

 its racemes of white flowers. It thrives best in a moist 

 sandy or peat soil. Increased, in spring, by seeds, or by 

 suckers ; and, in summer, by layers. 

 Z. virginica (Virginian), fl. white; racemes simple, terminal. 



June. I. alternate, simple, oblong, pointed, minutely serrate. 



ft. 6ft. to 7ft. North America, 1744. (B. M. 2409.) 



IVT. See Hedera. 



IXANTHUS (from Ixos, Mistletoe, and anthos, flower ; 

 in reference to the glutinous nature of the flower). OBD. 

 GentianecB. A monotypic genus. The species is an erect 

 greenhouse biennial herb, native of the Canary Islands. 

 It thrives in well-drained fibrous loam, and requires a 

 light, airy place in a cool greenhouse. Propagated by 

 seeds, sown in spring. 

 Z. viscosa (clammy), fl., corolla yellow, salver-shaped; tube 



white, twice the length of the calyx ; limb five-cleft. June and 



July. I. ovate-lanceolate, quite entire, three or five-nerved ; 



upper ones often connate. Branches opposite, crossed. Stem 



erect. A. 1ft. to IJft Canaries. (B. M. 2135, under name of 



Gentiana viscosa.) 



IXATJCHENTJS. A synonym of Lagenophora 

 (which see). 



IXIA (from ixia, the Greek name used by Theo- 

 phrastus for birdlime ; referring to the clammy juice). 

 SYN. Wurthia. Including Morphixia. OBD. Iridece. 

 A genus containing about twenty-five species of pretty 

 greenhouse (or hardy in sunny, sheltered, dry spots, in 

 the extreme south of Britain) bulbous plants, all natives 

 of South Africa. Flowers in simple or branched spikes ; 

 perianth tube long, slender; limb regular, salver-shaped. 

 Leaves narrow, ensate. Stems slender, simple or slightly 

 branched. Propagation is readily effected by seeds ; or 

 by offsets, which are freely produced. Seeds should be 

 sown in pans of sandy soil, about September, and placed 

 in a cool frame. The young plants may remain in the 

 seed-pans for the first year, when they should be either 

 potted singly or planted out. It takes from three to 

 four years before they flower. By growing a number of 

 varieties together, and saving their seed, numerous other 

 sorts may be obtained, usually much varied in colour, 

 and in the markings of the flower. Propagation by 



Ixia, continued. 



offsets is a much quicker method, as the plants then 

 generally flower the second year. Offsets may be secured 

 in quantity after the parent Ixias have ripened off, and 

 they should be stored in a dry place, until starting time, 

 the following autumn. 



Cultivatton in Pots. Ixias, cultivated as pot plants, 

 are very attractive, and admirably adapted for conserva- 

 tory and cool greenhouse decoration, in early summer. 

 The bulbs should be potted rather firmly, in sandy loam 

 and leaf soil, during October, placing about six or eight 

 in a Sin. pot, and covering them with lin. of soil. The 

 pots may then be plunged or stood on ashes in a cool 

 frame, and but little water will be required throughout 

 the winter. When the flower- spikes appear, more water 

 may be given, and the plants fully exposed to light and 

 plenty of air : draughts, however, must be avoided. After 

 flowering, growth and a gradual ripening should be en- 

 couraged, by keeping the plants watered for a time. 

 When the leaves die away, the bulbs may be shaken 

 out and stored in bags until the autumn, or they may 

 be allowed to remain in the soil and be kept dry. 



Where the cultivation of Ixias is attempted outside, a 

 well-drained, sunny, south border should be selected, and 

 the bulbs planted about 6in. deep, in autumn. They 

 should be lifted annually after being ripened, unless the 

 locality is favourable enough to ensure their safety when 

 left outside. Ixias do not require much heat, and, more- 

 over, do not succeed well in a high temperature. 



I. aulica (courtly), fl. rose-coloured, numerous ; spathe almost 

 equal to the tube. April. A. 2ft. 1774. SYN. Morphixia aulica. 

 (B. M. 1013, under name of /. capillaris aulica.) 



I. Candida (white). A synonym of /. leucantha. 



Z. capillaris (capillary).* fl. flesh-colour or lilac ; spathe scarious, 

 membranous, paper-like, having five rib-like streaks ending in as 

 many teeth, ApriL A. lift 1774. SYN. Morphixia capillaris. 

 (B. M. 617.) 



Z. columellaris (pillar-formed), fl. striped ; filaments united at 

 base. August, h. 6in. 1790. (B. M. 630.) 



I. flexnosa (bending-stalked). fl. pink ; tube slender, a little 

 enlarged ; limb below bell-shaped, contracted. April and May. 

 A. 2ft. 1757. (B. M. 624.) 



Z. fucata (painted), fl. pink, salver-shaped ; tube clavate, straight ; 

 spike one or two-flowered. June and July. 1. grass-like. A. 1ft. 

 1779. (B. M. 1379.) 



Z. nybrida (hybrid).* fl. white ; raceme flexuose, many-flowered. 

 April and May. J. slender. A. 1ft. 1757. (B. M. 127, under name 

 of /. flexuosa.) 



Z. lencantna (white-flowered), fl. white, one-sided; spathes 

 toothed, shorter than the tube. May. 1. linear-ensiform. A. lift. 

 1779. SYNS. /. Candida, I. patens leucantha. 



Z. linearls (linear), fl. scentless ; outer valve of spathe sub- 

 truncate, streaked with three brown veins ending in short teeth ; 

 segments of perianth striped with three longitudinal darker- 

 coloured veins. April. SYN. Morphixia, linear^. (B. M. 570, 

 under name of I. capillaris gracUlima.) 



1. maculata (spotted).* fl. orange-coloured ; limb spreading, 

 spotted at base ; stigmas not divided lower than base of anthers. 

 April and May. A. 1ft 1757. (B. M. 539, under name of 

 I. conica.) 



I. m. ochroleuca (yellowish- white), fl. cream-coloured, in spiked 

 heads ; tube shorter than segments. May and June. I. linear- 

 ensiform. A. 2ft 1780. (B. M. 539 ; A. B. E. 50, under name of 

 1. capitata.) 



Z. monadelpha (monadelphous). fl. blue ; filaments united in a 

 tube. April and May. h. 6in. 1792. (B. M. 607.) 



Z. odorata (sweet-scented).* fl. yellow, very fragrant; corolla 

 salver-shape ; limb longer than the spathe ; segments almost 

 equal; spike many-flowered. May and June. A. 1ft. 1757. 

 SYN. Morphixia odorata. (B. M. 1173, under name of /. erecta 

 lutea.) 



Z. patens (spreading-flowered).* fl. pink ; tube filiform ; limb 

 bell-shaped, spreading ; stigmas longer than the anthers. April. 

 A. 1ft. 1779. (B.M.522.) 



I. p. leucantha (white-flowered). A synonym of I. leucantha. 



I. polystachya (many-spiked), fl. variegated ; limb spreading, 

 not spotted ; stigmas divided as low as the tube. May and June. 

 A. IJft. 1757. (A. B. R. 155.) There is a variety jtavescens. 



I. reflexa (reflexed). A synonym of Tritonia scillaris. 



I. speciosa (showy).* fl. dark red ; limb hemispherical, cam- 

 panulate ; stigmas longer than the anthers. May and June. 

 h 6in. 177& (B. M. 594, under name of /. crateroides.) 



