ONCIDIUM 



Pseudobulbs usually present, wanting in a few spe- 

 cies, 1-2-lvd., with sheathing Ivs. at the base: Ivs. plane, 

 terete or triangular: petals like the dorsal sepal but 

 often much larger; lateral sepals either free or par- 

 tially united; labellum variable, but never with its base 

 parallel to the column (Odontoglossum), spreading 

 nearly at right angles to the column : column short, 

 winged. 



As a class, Oncidiums are short-lived under cultiva- 

 tion. Few growers succeed in maintaining them in 

 good condition for any great length of time. The stock 

 is constantly renewed from the tropics. 



HEINRICH HASSELBBING. 



The genus Oncidium embraces a great number of 

 species which are found growing under such peculiar 

 and varied conditions in their native homes that imita- 

 tion of the same is usually impracticable and often quite 

 impossible. A fair degree of success, however, may 

 T)e obtained by careful observation and distribution of 

 the exceptionally difficult species among the several 

 orchid departments. 



The Sarcoptera section, which embraces such species 

 as O. Cavendishianum, O. Lanceanum, O. luridum, O. 



ONCIDIUM 



1129 



1523. Oncidium serratum (X K). 



pulvinatum and others of similar structure, and the 

 O. Papilio section, with O. ampliatum, may be suc- 

 cessfully grown in a bright, warm portion of the 

 Cattleya department in small baskets suspended from 

 the roof, using for a compost a mixture of clean chopped 

 peat and sphagnum moss, freely interspersed with 

 lumps of broken charcoal. 



O. cucullatum, O. incurvum, O. macrawthum, O. 

 ornitJiorhynchum, O. Phalcenopsis, O. varicosum, with 

 a few others of like nature, do well under treatment 

 similar to that given for Odontoglossums, which see. 



When a large collection of species is cultivated, a 

 majority, including many of the above, can be readily 

 grown in one house if it be especially adapted to them. 

 Such a house should be a span-roof structure of east 



and west exposure, at an angle of about 40, which will 

 admit the longest possible light. The early morning 

 and late afternoon sun striking the glass at right angles 

 produces and prolongs the natural sun heat for a greater 

 portion of the day, while at midday, when the outside 

 temperature is highest, the sun's rays strike the glass 

 obliquely, giving less heat, with little danger of the 

 plants becoming sunburned from lenses in the glass. 

 Oncidiums require more sun and air than most orchids. 



The benches may be of either wood or stone, and 

 should be covered an inch or two in depth with sand 

 ashes or gravel. The benches and paths should be 

 wet down once or twice daily to insure a moist atmos- 

 phere. Ventilators should be arranged on both sides of 

 the roof: air may then be freely admitted without caus- 

 ing direct drafts on the plants by using the ventilators 

 on the sheltered side. In winter the temperature should 

 range from 50 to 55 F. at night and 60 to 65 by day, 

 or a few degrees more with sun heat and ventilation. In 

 summer it must be kept as low as outside conditions 

 will permit. From March until October shading must 

 be applied to the glass sufficiently heavy to keep down 

 the temperature without excluding indirect solar in- 

 fluence. A good shading is made of turpentine and 

 white lead; it stands well and is easily removed. It can 

 be applied rapidly with a whitewash brush on a long 

 pole, and removed with a hard brush in the fall. 



Oncidiums may be grown in either pots or baskets, 

 but as many species are of rambling habit, the latter are 

 preferable. The tiny species, such as O. Limminghii, 

 do best on blocks with little compost beneath them. 

 Clean chopped peat fiber and live sphagnum moss, equal 

 parts, make the best general growing material, and 

 this should be liberally interspersed with broken pieces 

 of charcoal. The plants in all cases must be securely 

 fastened, and the compost must be pressed in moder- 

 ately firm, but should be used sparingly. Overhead 

 syringing should be given frequently, once or twice a 

 day in bright weather, but care must be taken not to 

 keep the compost too wet, or the roots are liable to de- 

 cay: it is advisable to let them dry out occasionally. 



Stock is increased by division or notching the rhizome 

 between the pseudobxilbs just before the growing season, 

 allowing three or four pseudobulbs to each piece and 

 separating the parts after the first growth is matured. 



For other cultural notes on the genus, see Veitch's 

 Man. of Orch. Plants, vol. 2, Section Oncidium, page 5; 

 Orchid Review 1:296, and Nicholson's Diet, of Gard. 

 2:483 - ROBERT M. GREY. 



Owing to the wide geographical distribution of the 

 Oncidiums, it is almost impossible to give any general 

 cultural directions for the whole group. We find that 

 the greater bulk of the Oncidiums succeeds admirably 

 in a Cattleya house, and by placing such varieties as 

 enjoy more heat and moisture in the warmest part of 

 the house, the balance of the Oncidiums are compara- 

 tively easy to take care of in any part of the structure 

 wherever light, air and moisture are maintained. The 

 following are a few enjoying more heat than the others: 

 Oncidium ampliatum, O. bicallosum, O. Carthaginense, 

 O. Cavendishianum, O. J^anceanum and O. luridttm. 



Oncidium varicosum, the most popular and most use- 

 ful of all the Oncidiums, delights in a position close to 

 the glass, especially under the ridge of the house, where 

 it receives an abundance of light and air, and in such a 

 position this plant will grow well and flower profusely. 

 Oncidium Papilio and O. Krameriawum do best grown 

 in baskets or on blocks and kept rather dry. 



The following thrive well in a cool house, such as an 

 Odontoglossum house: Oncidium macranthum, O. orni- 

 thorhynchum, O. incurwim, O. tigrimim and O. cuculla- 

 tum. The first mentioned is one of the most beautiful 

 of the entire genus, but being a plant very difficult to 

 import, very few are seen in collections in this country. 

 It occurs at a very high elevation in the Cordilleras of 

 Ecuador. 



Oncidium cucullatum is another plant which is diffi- 

 cult to grow successfully here on account of our hot 

 summers. It occurs in several places in the Colombian 

 Cordilleras, but always at a very high elevation. With 

 these few exceptions mentioned, the greater part of the 

 Oncidiums will succeed in a Cattleya house. Indeed, 

 most of the species are found in the Cattleya and Laelia 



