DISTEIBTJTION OF THE MOEE PEOMINENT NATUEAL OEDEES. 271 



sufficient to refer to it here. They enumerate, however, some half a dozen species of 

 Ilabenaria, Spiranthes, and Microstylis which inhabit the peak of Orizaba at elevations 

 of 11,500 to 12,800 feet. 



The proportions of the tribal representation of orchids present no very remarkable 

 features. All the tribes are there, and the Epidendreae and Vandeas in nearly equal 

 numbers. Of the former there are thirty-seven genera and 440 species, 182 of which 

 are JEpidendrum itself, and there are fifty-six of Pleurothallis. The Vandese are repre- 

 sented by fifty genera and 370 species, Oncidium and Odontoglossum being charac- 

 teristic, and numbering respectively seventy-two and forty-two species. The Neottiese 

 comprise 100 species, belonging to fifteen genera, eight of which extend beyond 

 America, six being widely diffused. Spiranthes (including Stenorrhynchus) is the 

 largest genus, having thirty-four species. Habenaria is the only genus of the Ophrydese, 

 the bulk of which are north temperate and South African. Finally the Cypripedieae 

 are represented by one species of the widely-spread genus Cypripedium, and three of 

 the singular Selenipedium. 



Bromeliacece. 



About 350 species, belonging to twenty-seven genera, of this distinct and wholly 

 American natural order of plants were known to Bentham and Hooker ; and upwards 

 of a fourth of them are found within our limits. Judging from recent collections from 

 Brazil and other parts of tropical America, the number of species, at least, will yet be 

 largely augmented. Many of the Bromeliacese are not easily dried, and collectors seem 

 to have neglected the less conspicuous species. They are essentially tropical plants, 

 and mostly epiphytal in habit, yet a considerable number ascend to temperate regions 

 in the mountains of Central and South America, and a few extend far beyond the 

 tropics in both hemispheres ; two or three inhabiting the island of Juan Fernandez. 

 Ten species of Tillandsia inhabit Florida, and one of these, T. usneoides, finds its 

 northern limit in Virginia, and is very generally spread in humid districts southward 

 through Mexico and the West Indies to Chili and Uruguay. It also reaches the Rio 

 Pecos in Texas, the western limit of the order in North America. In appearance it 

 resembles a lichen or moss, its flowers being small and inconspicuous, and trees are 

 often completely clothed with it, even high up in the mountains. Another species, 

 T. recurvata, inhabits Florida, Texas, Mexico, the West Indies, extending southward 

 to Buenos Ayres ; and several other Mexican species are also found in the West Indies 

 and South America ; still the majority of the Bromeliaceae are rather restricted in their 

 range, and many are apparently quite local. It is noteworthy that the widely- 

 dispersed species have, for the greater part, comparatively inconspicuous flowers. On 

 the other hand, the Bromeliaceae generally are unsurpassed in the vegetable kingdom 

 for brilliancy of colouring, and the striking contrasts of colour exhibited by their 

 flowers and also often by their leaves. Tillandsia usneoides is perhaps the humblest 



