ODONTOGLOSSUM 



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 iniury; during 

 summer it must be kept as low as the outside tempera- 

 ture 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 O. Londesboroiighianum and O. coro- 

 nariiim. with long creeping rhizomes; O. eitrosnnim, 

 whicli liMs ]H'ii.lul..ns flower-scapes, and some of the 

 smaili'i- [.'lowing' s|i.cies, such as the O. Sossi section, 

 which iirc iiii.ic- .M-ily cared for under basket culture. 



Repotting' shcul.l be attended to in October and No- 

 vember, 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, 

 O. gloriosum, O. cirrhostim, O. liiteo-purpureiim, O. 

 Pescatorei, and kindred species, require an abundance 

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

 never dry out, and iudicious 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 time allowing free ventilation to ensure good 

 atmospheric action. Weak liquid cow manure during 

 the flowering period is also of assistance. 



Species of the O. grande section do not require as 

 much water at the roots as the O. erispwm type ; the 

 compost should be allowed to dry out frequently. They 

 are also benefited by a little sun during winter. 



O. citrosmum is an exception to the genus as regards 

 temperature, 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. 



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 morning and evening with a 

 lantern. 



For other cultural notes on Odontoglossums. see 

 Orch. Rev. 4:22. Robei;t M. Grev. 



Cool Oilniitoritossiiw.'s.-The management of the tropi- 

 cal Odc.iit.i-I.'vsuni^ found in high altitudes is one of 

 the iii"^t cliili.iilt and fascinating problems in orchid 

 culturr. Nearly all American collections of them have 

 decriasi-il anil liavf had to be refreshed from the tropics. 

 The collection of H. H. Hunnewell, at Wellesley, Mass., 

 has long been noted, although it has decreased in the 

 last twelve years. The undersigned has been asked to 

 give an account of the methods by which F. L. Harris 

 long maintained this fine collection with perhaps less 

 decrease than in any other collection in the country. 



The great problem, of course, with these plants is to 

 keep them cool enough in summer. The difliculty will 

 probably never be wholly solved until the advent of 

 artificial refrigeration. Shading alone is insuflicient. 

 The best principle to take advantage of is the coolness 

 produced by the rapid and excessive evaporation of 



ODONTOGLOSSUM 



1113 



How to produce a great and constant evaporation is, 

 then, the particular problem, and Mr. Harris' device 

 was an exceedingly ingenious one. Back of his Odon- 

 toglossum house he had a brick wall covered with Eng- 

 lish ivy, and he had water dripping over the whole vine 

 during hot weather. This gave him an extraordinarily 

 large evaporating surface. 



In general, it may be pointed out that the conventional 

 water pan gives a relatively small evaporating surface. 

 A gravel bed yields a far greater evaporating surface. 

 As an illustration, the undersigned would cite his own 

 experienc-p at the Buffalo Botanic Garden. There was 

 ali.mv,. iiiiiit f,.r I'ictoria regia and other tender aquatics, 



whi.li wa- 111 ciipied during winter. An attempt was 



itiaili' til mill, I iliis space in growing palms. The water 

 tank was hoank'd over for the palms, but the water 

 below did not furnish enough atmosphnic- incistiin- for 

 the palms, and they had to be reni'i\i.l. 'IIk' IkuiIiIc 

 was that the water in the big tank, b.in^' mliLi Than the 

 air, actually acted as a condenser, 'rin' m \t wintir the 

 tank was again boarded over, but the water in the tank 

 was drawn off and the floor co%-ered with a 6-inch layer 

 of gravel. The results were entirely satisfactory. 



J. F. COWELL. 



With Odontoglossums we have had good results the 

 past season by using what we call the Cookson formula. 

 recommended by Mr. Norman C. Cookson in the "Orchid 

 Review" for May, 1899. The formula is as follows: 

 Three ounces of potassium nitrate and 2 ounces of am- 

 monium phosphate, dissolved in a 3-gallon jar of soft 

 water. In watering any orchids when making their 

 growth, or when flowering, 1 ounce of the solution is 

 added to each gallon of water used. In the experience 

 of the writer, the above mixture is the best food met 

 with for cool orchids. In time it will probably bring 

 the plants into such a vigorous state that they will be 

 able to stand our hot summers without so much suffering. 

 A. J. Newell. 



Synopsis of Sections. 

 A. Fls . yellow , variously spotted with broun, crimsoH,etc. 

 Section I. Ground color of the labellum yellow. 



Species 1-14 



Section II. Ground color of the labellum white, 



rarely pale yellow or changing to yellow. Species 15-28 



AA. Fls. white^ sometimes shaded with rose or cream, 

 never uith a bright yellow or greenish yellow 

 ground color. 

 Section III. Plants not dwarf: fls. numerous, in 



branched panicles much exceeding the Ivs 



Species 29-34 



