AN ENCYCLOPEDIA OF HORTICULTURE. 



483 



Omphalodes continued. 



with denticulated, ciliated margins. Branches terminating 

 in loose racemes, h. 6in. to 12in. South Europe &c., 1748 

 Annual. 



O. Lucilioe (Lucilia's).* fl. lilac-blue, nearly Jin. in diameter, 

 much larger than those of 0. verna. Summer. I. oblong-obtuse, 

 radical ones narrowed into a long footstalk ; cauline ones sessile, 

 and the upper ovate, h. 4in. to 6in. Mountains of Greece 

 and Asia Minor, 1873. A handsome perennial rock plant. 

 (B. M. 6047.) 



O. nltida (shining). /. white ; racemes very long, ebracteate ; 

 pedicels and calyces adpressedly pilose. May. 1. oblong-lanceo- 

 late, nerved, glabrous and shining above, pubescent beneath ; 

 lower ones long-stalked ; upper ones sessile. Stem erect, 

 branched, glabrous, h. 2ft. Portugal, 1812. Perennial. (B. M. 

 2529.) 



O. verna (spring).* fl. blue, with a white throat, distant, on long 

 pedicels ; racemes bractless, conjugate, few-flowered. March to 

 May. I., radical ones ovate-cordate; cauline ones ovate-lanceo- 

 late, petiolate. h. bin. South Europe, &c., 1633. A well-known 

 and extremely pretty perennial, which, when fairly established, 



makes rapid growth, increasing itself by runners, somewhat 

 like Strawberry plants. S 

 Cynoglossum Omphalodes.) 



, , 



plants. See Fig. 727. (B. M. 7, under name of 



OXAGRARIE2E. An order of inodorous, annual 

 or perennial herbs, rarely shrubs or trees, a few being 

 aquatic. They are found in all temperate regions, but 

 are rare in the tropics. Flowers generally hermaphro- 

 dite, usually axillary and solitary, or else spicate or race- 

 mose at the tips of the branchlets, rarely paniculate; 

 calyx tube adnate to the ovary ; lobes two or four, rarely 

 five or six, valvate; petals often two or four (rarely 

 none), inserted at the base of the disk, fugacious, twisted. 

 Fruit capsular, nut or berry-like. Leaves opposite and 

 alternate, membranous, entire or rarely pinnatifid, 

 sometimes toothed or serrated ; stipules none. The 

 species contain mucous and, occasionally, somewhat 

 astringent principles. The berries, as a rule, are sweet 

 and edible ; while the roots of several species of (Enothera 

 are also eaten. The order comprises twenty-two genera 

 and about 300 species. Illustrative genera are : Fuchsia, 

 Gaura, (Enothera, and Trapa. 



ONCIDIUM (from onkos, a tumour; referring to the 

 warty crest on the base of the labellum). OBD. Orchide<s. 

 A. large genus of epiphytal Orchids, inhabiting tropical 

 America and the West Indies. Over 250 species have 

 been described, and a large proportion of these have 

 been, or are still, cultivated in English collections ; whilst 

 additions are being frequently made, both to the number 

 of species and to those in cultivation. The flowers show 

 remarkable variety, both as regards size, form, and 

 colour; in the latter, yellow predominates. They are 

 borne either in long, flexuose racemes, or in dense, 

 clustering spikes, a few being distinguished by one- 

 flowered scapes ; peduncles from the base of the matured 

 pseudo - bulbs generally accompany the new growth. 

 Leaves variable in size and form, often thick and leathery, 

 sometimes thin and papery. Pseudo - bulbs generally 

 compressed laterally, ovate-oblong, rotundate, or cylin- 

 drical; in a few species almost or entirely suppressed. 



From an altitude of 12,000ft. or 14,000ft., where snow 

 and frost are frequent, and where, at all times, the 

 atmosphere is cool, and laden with moisture, several of 

 our popular garden Oncidiums are obtained ; and from this 

 extreme elevation, down to the hot, moist valleys of 

 the most tropical parts of America, the species are 

 found luxuriating under very varied conditions. Some 

 of them grow well only when kept in bright sunlight 

 and a tropical temperature, whilst others require shade, 

 with a medium amount of heat and moisture; others, 

 again, thrive only when kopt quite cool and moist, and 

 placed out of the reach of direct sunshine. 



The wide range of distribution over which the On- 

 cidiums extend, and the often wide difference in the 

 conditions under which they grow in a state of nature, 

 suggest that, for their cultivation here, houses of both 

 tropical and intermediate, as well as cool, temperatures 

 are necessary, if a representative collection is to be 



Oncidium continued. 



grown. Taking, first, the tropical species, of which O. 

 Cavendishianum, O. Lanceanum, and 0. Papilio may be 

 cited as examples, it will be found that, to grow these 

 well, a moist stove is necessary, and that, during the 

 season when growth is most vigorous, the conditions 

 requisite in the case of East Indian Orchids must be 

 maintained for these tropical Oncidinms. During winter, 

 the temperature may be lowered to that of an inter- 

 mediate house, viz., from 55deg. to 60deg. in the day, 

 and 50deg. at night, and the moisture in the air and at 

 the root be reduced to a minimum. The large-leaved, 

 strong-growing species are best managed when planted 

 in baskets or pots, with a good quantity of peat, 

 sphagnum, and charcoal about their roots; whilst the 

 smaller kinds may be fastened on to rafts or blocks, and 

 suspended near the glass. These last must be watched 

 during warm weather, and prevented from becoming 

 parched ; a dip in a pail of water once or twice a day 

 being good for them, even when growing in a house 

 where a continual, moist atmosphere is maintained. 



The species requiring what is termed an inter- 

 mediate house, such as is usually provided for Cattleyas, 

 or even where shrubby Begonias are grown, may be 

 treated as advised for the above as regards moisture, 

 light, potting or rafts, and rest. A considerable number 

 of Oncidiums belong to this intermediate section, some 

 of the most familiar of them being O. crispum, 0. Jonesi- 

 anum, 0. macranthum, O. Marshallianum, 0. serratum, 

 0. varicosum, &c. Probably, the most beautiful of the 

 Oncidiums are to be found in this group, and if a 

 collection of them were selected from those enumerated 

 below, the wonderful form and exquisite beauty of their 

 flowers would be a source of much greater delight than 

 is generally understood to belong to the genus. The 

 distinct and handsome 0. Jonesianum is somewhat 

 exceptional in its requirements, as it makes its growth 

 during our autumn and winter, and should be kept 

 as cool and dry as possible from April to September, 

 the period when almost all the other kinds are growing 

 vigorously. 



Of the really cool species, there are yet many of re- 

 markable beauty and distinctness. As they may be 

 grown in a house or pit, from which in winter frost 

 alone is excluded, and in summer the temperature kept 

 cool, and the air as fresh and moist as possible, they 

 may be enjoyed by those who do not care to provide 

 heated structures for Orchids. Some of them for in- 

 stance, 0. cucullatum and its forms are found at very 

 high elevations, where frost is frequent ; and 0. cemulum 

 is equally cool in its native haunts. They require plenty 

 of moisture, both at the root and in the air about 

 them, all the year round ; and generally, they succeed 

 best when planted in pots, using for this purpose a 

 mixture of peat, sphagnum, and charcoal. 



Propagation is effected by division of the plants. A 

 few of the species which produce long flower-racemes 

 develop young plants in the axils of the branches of 

 these, as in the genera Epidendrum and Phalcenopsis. 



In the following list of species, those marked T. are 

 tropical, and require stove treatment ; while those marked 

 C. will thrive in a cool house. The remaining species 

 require an intermediate temperature. 



O. acinaceum (scimitar-shaped). /. about lin. across; sepals 

 white ; petals large, violet, bordered with white ; lip the same 

 colour, shaded with carmine ; spikes from 1ft. to 2ft. long. Peru, 

 1866. A distinct and elegant species. 



O. semulum (rivalling).* /. very large ; dorsal sepal of a warm 

 cinnamon colour, nearly reniform in shape ; lateral sepals longer, 

 of a yellowish-brown or cinnamon colour ; petals very bright 

 cinnamon, all the segments nicely crisped or wavy : lip marked 

 with purple-violet, yellow at its base, with reddish-brown streaks. 

 Peru, &c., 1872. A vigorous-growing species, a worthy rival to 

 0. macranthum. (B. M. 5980.) [C.] 



O. alcicorne (stag's-horn). fl. yellow, with pallid streaks, 

 panicled. I. ligulate. Pseudo-bulbs oblong, ancipitous. New 

 Grenada, 1872. 



