July 20, 1888.] 



SCIENTIFIC NEWS. 



59 



Natural fgfttot^* 



THE ORCHIDS: WHAT ARE THEY? 



(Continued from p. 36.) 



Among the cultivators of orchids these plants are com- 

 monly divided into a " cool " and a " hot " group, 

 a classification based, not upon any structural dis- 

 tinction, but upon the temperature which they re- 



Odontoglossum, Cattleya, and Laelia. The first-mentioned 

 genus includes some of the most popular species of the 

 entire family. Some idea of its general structure may be 

 formed from our figure on p. 35, though even carefully 

 coloured illustrations can convey but an imperfect con- 

 ception of the beauty of most of the plants. The 

 technical characteristics of Odontoglossum are : sepals 

 spreading and free, the lateral ones rarely united at 

 their bases ; petals generally of the same size as the 

 sepals, though sometimes broader ; lip, parallel with the 



Odontoglossum Grande. (After Veitch.) 



quire. The "cool" orchids are almost exclusively 

 natives of the western hemisphere, where they extend 

 from lat. 20 N. to 30° S. In South and Central 

 America, high temperatures of course prevail in the 

 plains, but the bulk of the " cool " orchidaceous plants 

 which we encounter in European conservatories 

 are natives of the mountains, some of them extending 

 to the altitude of 9,000 feet above the sea-level, whilst 

 some of the small-flowering species which grow not 

 on the trunks of trees, but upon rocks, or even in the 

 ground, like the orchids of Europe, may be found at 

 heights even of 11,000 or 12,000 feet. 



Of the " cool " orchids the most noteworthy genera are 



column at the base ; the intermediate lobe or limb, 

 either spreading or deflexed, and furnished with a fleshy 

 crest near the base. Column, club-shaped, often 

 elongate, usually narrow at base, sometimes expanded 

 into a membranous wing on each side, or into auricles at 

 base, or wingless. Pollinia, two, pear-shaped or ovoid, 

 united by a linear or flattened caudicle to an oval viscid 

 disc or gland. Capsule variable in form, but usually 

 ovoid or oblong, and often rostrate. 



As regards their colouration, we may say that Od. 

 blandum, the species which we figured in our last number, 

 has its sepals and petals white, spotted with reddish 

 purple, whilst the white lip displays bright yellow streaks. 



