ODONTOGLOSSUM 



ODONTOGLOSSUM 



2321 



natives of the higher regions of the Andes from Mex. 

 and Guatemala to Colombia, Bolivia and Peru. 



This genus is closely related to Oncidium and Mil- 

 tonia, some of the species of the latter being generally 

 cultivated as odontoglossums. These two genera are 

 easily distinguished from Odontoglossum by the label- 

 lum, which expands directly from the base of the 

 column. There is perhaps no genus of orchids in which 

 the species are more variable and more closely related 

 than in Odontoglossum. Numerous varieties connect 

 the species by intermediate links, and the occurrence of 

 many natural hybrids makes the limitation of species in 

 this genus almost impossible. However much this may 

 add to the perplexity of the botanist, it gives the genus 

 an additional horticultural value and interest resulting 

 in the production of numerous garden hybrids and in 

 the selection of many varieties, one species, O. crispum, 

 having over a hundred named kinds. 



Cultivation of odontoglossums. 



Odontoglossums follow the high western mountain 

 ranges from southern Mexico to southern Peru, and 

 usually grow at great altitudes. With few exceptions, 

 they are found in extremely moist situations where the 

 annual rainfall is excessive and the temperature more 

 or less even and cool throughout the year. 



The extreme heat of our summer interferes somewhat 

 with the culture of odontoglossums in America, espe- 

 cially those of the 0. crispum section, and it is neces- 

 sary to use every precaution during that season to 

 insure success. 



A lean-to or half-span roof structure of northern 

 exposure, protected by a brick or stone wall on the 

 south side, and with ample means of ventilation, is best 

 suited to Odontoglossum culture. Moreover, it should 

 be provided with rolling shades elevated on framework 

 18 or 20 inches above the glass, to afford abundance of 

 light, free access of air and requisite shade, with the 

 additional assistance of keeping down the temperature 

 in summer. The interior is best fitted with solid beds, 

 if possible, but benches of stone flags or wood covered 

 with ashes or gravel an inch or two deep will answer 

 very well. These, with the floors, should be hosed 

 down two or three times daily, to keep the house as 

 cool and as moist as possible. 



Ventilation is highly essential at all times, especially 

 in dull or wet weather. When the atmosphere is over- 

 charged with moisture, the quantity must be governed 

 by outside conditions. Top ventilation is most satis- 

 factory, because it allows the heated air to escape, gives 

 less direct draft on the plants, and does not have the 

 drying effect produced by side currents. 



The temperature during winter should never rise 

 above 65 F., even with mild sun heat, and may fall 

 to 48 or 50 at night, or even lower, without injury; 

 during summer it must be kept as low as the outside 

 temperature will admit. Fire heat should be dispensed 

 with as early as possible in spring. 



Odontoglossums do well under pot culture, excepting 

 a few, such as 0. Londesboroughianum and O. brevifolium, 

 with long creeping rhizomes; 0. citrosmum, which has 

 pendulous flower-scapes, and some of the smaller-grow- 

 ing species, such as the 0. Rossii section, which are 

 more easily cared for under basket culture. 



Repotting should be attended to in October and 

 November, never during the summer months. Chopped 

 fibrous peat, live sphagnum and clean decayed leaves 

 in equal quantity, well mixed together, afford a very 

 satisfactory compost. About one-half of the pot space 

 should be devoted to drainage of charcoal or broken 

 potsherds. The plants should be firmly potted, leaving 

 the surface slightly convex, thus elevating the base of 

 the plant a little above the rim of the pot when finished. 



The O. crispum section, which includes O. Coradinei, 

 0. gloriosum, 0. cirrhosum, 0. luieo-purpureum, 0. 



147 



nobile, and kindred species, requires an abundance 

 of water at all seasons; in fact, the compost should 

 never dry out, and judicious light overhead syringing 

 once a day is beneficial in bright weather, but on very 

 warm days it should be applied in the evening, at the 

 same tune allowing free ventilation to ensure good 

 atmospheric action. Weak liquid cow-manure during 

 the flowering period is also of assistance. 



Species of the 0. grande section do not require so 

 much water at the roots as the 0. crispum type; the 

 compost should be allowed to dry out frequently. They 

 are also benefited by a little sun during winter. 0. 

 citrosmum is an exception to the genus as regards tem- 

 perature, and should be grown 10 warmer. It does 

 very well in the cattleya department, enjoys a good 

 supply of water at the roots at all seasons, and may be 

 easily induced to flower freely by giving it a sunny loca- 

 tion during winter. 



Very few of the species can be satisfactorily propa- 

 gated by division; the trade depends principally on 

 fresh importation, and they come readily from seeds. 

 (See the article on Orchids, beginning page 2380, for dis- 

 cussing of seed-growing methods of orchids in general.) 



Among the worst enemies of odontoglossums are 

 slugs and the small shell snails. They destroy the ten- 

 der flower-scapes, often attacking them even in the leaf- 

 sheath. A piece of cotton wrapped about the base of 

 the pseudobulb will afford a means of protection, and 

 many may be caught by distributing bits of apple, 

 potato, or saucers containing dry bran freely among the 

 plants. Look them over in the morning or evening with 

 a lantern. ROBERT M. GREY. 



Cool odontoglossums. 



There has been a large measure of success attained 

 in the culture of these Andean plants in several instances 

 and near the seashore, or during a cool summer season. 

 The plants do well under special conditions, such as a 

 structure facing north, with ample shade by using 

 roller-blinds a foot or more above the glass roof, and 

 by using a spray of water on very hot days either under 

 the benches or hi the path, ejected with force to create 

 a spray and cause rapid evaporation. Perforated pipes 

 have been used, but these soon clog up and are inef- 

 fectual. It is best to turn off the spray at night as the 

 outside air will be cooler. It is best in winter to bring 

 the plants to a lighter house where they can get all the 

 sun in the dull months, as most of the growth is made 

 during the winter and needs to be well matured and 

 strong to carry the plants through the flowering period 

 of early summer months. In March, there are very 

 bright days when a little shade is necessary, and early 

 in April removal should be made to summer quarters 

 in the coolhouse proper. One very hot summer has 

 been known to undo the upbuilding of several preceding 

 cool ones. Odontoglossums are freely raised from seeds 

 by the hybridist hi Europe, but have never been raised 

 in the American collections. Their seeds germinate the 

 readiest of any orchids, coming up like grass in a few 

 weeks after sowing, but invariably go down again dur- 

 ing the heat of "dog days" in summer. The hybrids 

 imported seem to have more vigor, especially those 

 that have 0. nobile as a parent. One of the most 

 wonderful phases of the hybridists' work is seen in the 

 great variety produced, the proving up of the origin of 

 many supposed species of Reichenbach and others, the 

 reproduction of fine types from seeds true to themselves 

 in a measure, but usually with an admixture of the 

 poorest present, showing the very complex origin of our 

 most beautiful garden orchids as they were found first. 

 The partial extinction of these odontoglossums by the 

 march of cultivation of coffee and other valuable crops 

 in the Andes has no longer any terror to the cultivator, 

 equally good forms now being raised in gardens, and 

 sometimes flowered in months rather than years. 

 There is still the element of uncertainty as to what will 



