468 



THE DICTIONARY OF GARDENING, 



Odontadenia continued. 



shrubs, natives of tropical America, mostly Brazil and 

 Guiana. Flowers yellow, showy, disposed in loose, often 

 large, rarely few-flowered and scarcely branched cymes; 

 calyx five-parted ; corolla funnel-shaped or sub-hypo- 

 crateriform. Leaves opposite, penniveined. 0. speciosa, 

 probably the only species in cultivation, perhaps does 

 best when planted out in a prepared border in the stove, 

 and the long shoots trained along the rafters. If cul- 

 tivated in pots, a fairly liberal amount of root-room 

 must be accorded; and thorough drainage is always 

 essential. Good turfy loam, pieces of charcoal, a hand- 

 ful of coarsely-crushed bones and sharp sand, make a 

 compost in which the species succeed well. Insects 

 must be kept in check by fumigation, or the use of 

 one or other of the insecticides mentioned in this work. 

 Odontadenias are propagated by cuttings of the young 

 shoots, which strike readily in bottom heat. 



O. speciosa (showy), fl. bright yellow, shaded with orange, 

 large, of good form, and delicately scented. I. large, oblong- 

 ovate, acute, quite smooth, dark green. Trinidad, 1854. SYN. 

 Dipladenia Harrisi. (B. M. 4825.) 



ODONTARRHENA. Included under Alyssum. 



ODONTOGLOSSUM (from odous, odontos, a tooth, 

 and glossa, a tongue ; referring to the tooth-like processes 

 on the lip). Including Mesospinidium (some of the 

 plants grown in gardens under the generic name of 

 Mesospinidium, belong to the genus Cochlioda). OBD. 

 Orchidece. This genus comprises, according to some 

 authorities, over one hundred species of handsome, stove 

 Orchids, inhabiting the Andes of tropical America, from 

 Bolivia as far as Mexico. Flowers with spreading, free 

 sepals; petals nearly equal; lip with its base parallel 

 with the column, and its limb deflexed and generally 

 crested in various ways ; column usually long, narrow 

 at the base, and eared, or winged, at the summit; pollen 

 masses two, with a narrow caudicle attached to an 

 oval gland. Leaves in nearly all the species ensiform, 

 usually sub-coriaceous in texture, linear-lanceolate or 

 simply lanceolate, complicate at base, tapering to a more 

 or less acute point. This genus is distinguished from 

 Oncidium by the column being long and narrow, or, at any 

 rate, not swollen, at the base, and by the base of the 

 lip being always parallel with the face of the column. 



For purposes of cultivation, the Odontoglossums may 

 be divided into two groups, comprising (1) all those 

 species which require the treatment of an intermediate 

 house, i.e., a temperature not lower than SOdeg. to 

 55deg. in winter, and correspondingly high in summer ; 

 and (2) those which will thrive in a cool house, from 

 which frost only is excluded, or, for safety, say, where the 

 temperature will not fall below 40deg. Many of these 

 plants, as well as other orchids, are found at very high 

 elevations, where, at some seasons, they are visited by 

 slight frosts and snow. Eecently, many species of Odonto- 

 glossum have been successfully cultivated out of doors 

 under the shade of trees, and where the atmosphere 

 about them could not become too parched. The plants 

 are hung up, either in baskets or on rafts, exactly as 

 when cultivated under glass, and are syringed frequently 

 in dry weather; they are not injured, but, on the 

 contrary, much benefited, by frequent showers of rain. 

 It is probable that, as these and other Orchids become 

 cheaper, they will be cultivated at much less cost 

 than at present, and no doubt outdoor cultivation, 

 for at least a portion of the year, will be adopted 

 for a great number of those from cool and temperate 

 climes. Even those from warmer regions would most 

 probably be improved by open-air cultivation during our 

 hot season. For the species requiring warm-house treat- 

 ment, and which are distinguished in the subjoined list 

 by a dagger (f), the following points must be attended 

 to. When making their growth, which is during the 

 summer, they require plenty of water, a position near 



Odontoglosstun continued. 



the glass, where they would be shaded only from bright 

 sunshine, and a moist atmosphere, with plenty of fresh 

 air about them, care being taken that the temperature 

 does not fall too low through the latter. During the 

 winter, they should be kept almost dry, and, in spring, 

 quite dry till the flower spikes appear, when water should 

 be applied liberally, and continued till the summer's 

 growth is again completed. 



The species grown in a cool house do not, as a rule, 

 require a resting season similar to the above, but 

 should be kept uniformly moist at the roots all the 

 year round; indeed, many of them grow freely all 

 through the winter. None of them like direct sunshine in 

 summer, but in winter they enjoy all the sunlight possible. 

 It is, therefore, a good plan to place the plants in a house 

 with a northerly aspect for the summer, whilst, on the 

 return of the cold, dull weather of winter, they may, 

 with advantage, be removed into a house with an aspect 

 due south. In the United States, the Odontoglossums 

 invariably make two growths a year, the one in summer, 

 and the other in winter, the latter being favoured by the 

 clear and bright light which prevails in North America in 

 winter. It should be remembered that, whilst very few 

 orchids certainly no Odontoglossums enjoy excessive 

 sunlight, they are, nevertheless, much healthier and 

 more floriferoua when grown in a house where they can 

 obtain all the light possible, short of the fierce sunlight 

 of our summers. Generally, Odontoglossums require a 

 moist atmpsphere at all times, and, after a bright day, are 

 much invigorated by a gentle dewing overhead by means 

 of a syringe. A few of the species, such as 0. Cer- 

 vantesii, 0. Londesboroughianum, 0. Rossii Dawsonianum, 

 &c., may be satisfactorily grown when fastened on to a 

 block, formed of fern stem ; but Odontoglossums succeed 

 best when grown in baskets or in pots, using a mixture 

 of peat (broken into lumps the size of walnuts) and 

 sphagnum, with a few lumps of charcoal and a little 

 sand scattered through it. Pots should be half-filled 

 with drainage, and baskets covered at the bottom with 

 a large crock, or a few pieces of charcoal. Bound the 

 top of the soil a little fresh sphagnum should be placed ; 

 it will soon grow, and cover the whole surface with a 

 fresh green, and prevent excessive evaporation in hot 

 weather. To establish newly-imported Odontoglossums, 

 they should be first carefully examined, and all dead 

 bulbs, scales, and roots cut away ; they may then be 

 rinsed in warm water, and allowed to dry, before placing 

 them in a little soil. The pots used should be as small 

 as possible, all that is necessary being room for the base 

 of the plant to stand in each with a little peat and 

 sphagnum about it. Very little soil must be used, the 

 pot being filled almost full of crocks; unless this pre- 

 caution is taken, there is danger of the weakened plants 

 being injured, and perhaps killed, by the water which 

 would be held about them by a large body of soil. They 

 should be placed in a shaded part of the house where they 

 are to be grown when established. It is not wise to 

 attempt to force the plants into growth by subjecting them 

 to a high temperature, as the effect of this, although 

 promising at first, is to weaken the whole plant by 

 causing it to start into growth before it has recovered 

 from the injuries caused by importation. All the Odonto- 

 glossums are propagated by division, none having, as 

 yet, been raised from seeds in this country. Mr. H. 

 Veitch, in his paper on the " Hybridisation of Orchids," 

 read at the Orchid Conference, on May 13th, 1885, says 

 that numerous crosses between various species, both 

 Mexican and New Grenadan, have been effected, and 

 capsules, with apparently good seed, have been pro- 

 duced ; but, with the utmost care that could be bestowed, 

 no progeny has yet been raised. 



The plants which are, perhaps, best known under the 

 names of 0. Phalaenopgis, O. Roezlii, O. vexillarium, &c., 



