DISTRIBUTION OF THE MOEE PEOMINENT NATUEAL OEDEES. 269 



was its probable reduction to nine. The species recorded from North Mexico are — 

 Meiracyllium gemma, Microstylis ophioglossoides, M. sp., Hexalectris aphylla, Govenia 

 andrieuxii, Odontoglossum madrense, Oncidium sphacelation, Spiranthes madrense, S. 

 polyantha, Pogonia sp., Habenaria leucostachys, and an unnamed species of Habenaria. 

 The Oncidium was included through a misprint in the Enumeration, and the Odonto- 

 glossum and Meiracyllium were put under North Mexico, because they were recorded 

 from the Sierra Madre ; but in all probability they are natives of South Mexico. This 

 being so, there would remain only terrestrial species belonging to genera extending 

 into the United States, except Govenia. Indeed America, north of Mexico, is extremely 

 poor in Orchids ; the whole country supporting only about two thirds of the number 

 found in Europe. Twenty-two are recorded from California, and, as a further illus- 

 tration of the range of the northern terrestrial genera, it may be added that, with the 

 exception of Calypso borealis, a North-European orchid, they all belong to British 

 genera. Fifty-six species inhabit the Northern United States, and sixty-two (including 

 upwards of a dozen tropical species in the extreme south of Florida) the Southern 

 States ; many of the species being common to both. The following northern species 

 enter Mexico * : — Epipactis americana, Habenaria repens, H. leucostachys, Hexalectris 

 aphylla, Microstylis ophioglossoides, Ponthieva glandulosa, and Spiranthes roman- 

 zoviana. The monotypic Hexalectris is the only genus of these restricted to North 

 America and Mexico. Of the non-endemic species of Mexican and Central-American 

 orchids 108 are known to extend into some part of South America, and 75 into the 

 "West Indies. In an order containing so large a proportion of endemic and local 

 species among those with which we have to deal, it may be interesting to give a list of 

 the few species having a wide area in America. To these may be added the northern 

 Spiranthes romanzoviana, which ranges northward through California to Kamtschatka, 

 and eastward through Canada to New York ; and also, as mentioned above, inhabits, or 

 did inhabit, South-western Ireland. 



In South Africa Orchidea? appear to occupy the fourth place in number of species, 

 and in Australia the seventh place ; in both regions terrestrial species largely predomi- 

 nate. Available data for comparison with the floras of Colombia, Brazil, and other 

 parts of South America are wanting ; but Grisebach gives the order the second place in 

 the West-Indian flora, and as constituting 6-7 per cent. Of the flowering-plants of 

 Trinidad known to him, 11 per cent, were orchids; but the orchid element had been 

 specially investigated. 



* After the completion of our distribution-tables we discovered that the additional Orchids in the Supple- 

 ment to Chapman's 'Flora of the Southern United States' had been omitted from our calculations. The 

 additional species are : — Epidendrum cochleatum, E. nocturnum, Polystachya luteola, Vanilla planifolia, and 

 Crytopodium punctatum ; all of them from the extreme south of Florida. This is a nominal addition of five 

 species and three genera to the numbers of Mexican species and genera extending into eastern North America ; 

 but, as explained elsewhere, the tropical forms found in South Florida have no special significance in relation 

 to the distribution of Mexican plants, being in reality a part of the West-Indian region. 



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