50 GENERAL REVIEW OF THE ORCHIDE^. 



number of sjiecies yet remain to be so minutely studied, we quite concur 

 Avitli Mr. Hemsley that Professor Pfitzer's classification is necessarily 

 incomplete, seeing liow many tropical species of orchids are only known 

 from imperfect specimens preserved in herbaria.* Nor is it quite clear 

 what practical end would accrue to systematic botany from a classification 

 foimded on a more complete examination even if it were attempted, since 

 the characters afforded by the vegetative organs can have but a subordinate 

 value in the systematic arrangement of the Orchidb.e or any other 

 family of phanerogamic plants. The highest division in which these 

 characters have been made available by ^Ir. Bentham in his revision 

 of the ORCHiDEiE for the Genera Plant arm a are his sub-tribes, t their 

 systematic value being in an inverse ratio to the rank of the group 

 or division in which they are used, and thence greatest as distinguishing 

 marks in the species and their varieties. 



Nevertheless, the priuiary divisions of Professor Pfitzer's classification 

 of the Orchidejt; as founded on the vegetative organs are very natural 

 ones and the best of their kind that have been proposed, and moreover 

 not devoid of practical value to the cultivator. On these grounds alone 

 they are ■worthy of attention, and we thence bring them before tlie 

 reader M'ith examples selecteil from each division restricted chiefly to 

 epiphytal species and the Cypripedib.e. 



These primary divisions are — 



I. — MoNOPODiAL Orchids. Those which grow continuously in one 

 direction only. Their stems lengthen indefinitely season after season, 

 and bear aerial (adventitious) roots often along their whole length. 

 The inflorescence is always lateral and is produced from the axils 

 of the leaves or opposite to them. 



II. — Sympodial Orchids. Those in which the growth of the main 

 axis, stem or pseudo-bulb soon ceases, usually at the end of one 

 season's growth, and a lateral growth is produced in the following 

 season. 



The Sympodial Orchids admit of a division into two groups — 



A. — Those bearing a lateral inflorescence. 



B. — Those bearing a terminal inflorescence. 



The nionopodial orchids form a comparatively small division ; they 

 include Bentham's sub-tribe Sarcanthe.e, and some species in other 

 sub-tribes not often seen in cultivation in other than botanic gardens 

 except Vanilla. Well-known examples of nionopodial orchids are afforded 

 by Vanda, Aiirides, Angraecum, Arachnanthe, Rhynchostylis, Saccolabium, 



* Gard. Chron. XVII. (1882), ^i. 341. 



+ See the sub-tribal characters of Pleurothalleae, Bletiete, Eulophiese, Sarcauthete, etc. 



