468 



SCIENCE. 



[N. S. Vol. XXIII. No. 586. 



THE TORREY BOTANICAL CLUB. 



The meeting of February 13 was called to 

 order at the American Museum of Natural 

 History, by the secretary, at 8:30 o'clock. 

 Owing to the absence of the president. Dr. N. 

 L. Britton was called to the chair. Twenty- 

 three persons were present. 



A paper by Dr. Arthur Edwards, on the 

 ' Origin of the Bacillaria,' was read by its title 

 and referred to the board of editors with 

 power. 



The paper of the evening was an illustrated 

 lecture by Mr. George V. Nash, on the ' Gen- 

 eral Botanical Features of Orchids.' 



There seems to be a general misconception 

 among many as to just what an orchid is. 

 Any plant which grows on a tree, or has some 

 peculiar feature is, without hesitation, called 

 an orchid. This mistake is frequently made 

 in regard to the pitcher plants. Nepenthes, or 

 to the tail-flowers, Ardhurium. In order 

 more clearly to define the structure of the 

 orchid flower, a large flower of the genus 

 Cattleya was illustrated on the screen. The 

 uniting in one organ, called the colv/mn, ai 

 the stamens and pistils, serves at once to dis- 

 tinguish this family from all related ones. 

 The diandrous and monandrous forms of this 

 column were described and illustrated with 

 lantern slides, as were the other features of 

 the family. The two kinds of pollinia were 

 explained, that which develops appendages at 

 the base, and that which is without append- 

 ages, or develops them at the apex, the former 

 associated with the persistent anthers, the lat- 

 ter with the deciduous anthers. Attention was 

 called to the thickened stems of most orchids. 

 In some the stem is very short and much en- 

 larged. Such stems are known as pseudo- 

 hulbs. Oncidium and Odontoglossum are ex- 

 amples of this sort. In others the entire stem 

 is thickened, as is the case in Cattleya and 

 Dendrohium. The lateral and terminal forms 

 of inflorescence were described, the former 

 arising from the base of the pseudobulb, the 

 latter from its apex. The venation of the 

 leaves, whether convolute or eonduplicate, was 

 illustrated. The manner of growth, whether 

 limited or unlimited, was indicated; the lim- 

 ited in such genera as Epidendron, Oncidium, 



Odontoglossum, Masdevallia and in fact the 

 greater part of the orchids; the other, the 

 unlimited, in such genera as Vanilla, and 

 Angrcecum, in which the axis ascends con- 

 tinuously. 



The latest comprehensive treatment of this 

 interesting family is by Pfitzer, in Engler and 

 Prantl's ' Natiirlichen Pflanzenfamilien.' In 

 his classiflcation he utilized the characters and 

 habits of growth referred to above. 



The orchid family is a large one, embracing 

 some 6,000 or 7,000 species, mostly distributed 

 in tropical regions. Comparatively few are 

 found in the warm temperate, and almost 

 none in the cold portions of the temperate 

 zone. The center of their distribution in the 

 old world is in India and the Malay region. 

 Such genera as Dendrohium, Vanda and Bul- 

 hophyllum represent these. In the new world 

 they are found in the greatest numbers in 

 Brazil and northern South America. Such 

 genera as Cattleya, Lwlia and Masdevallia 

 illustrate these. In the United States there 

 are about 150 species, representing 44 genera. 

 These are mainly terrestrial, the comparatively 

 few epiphytes being confined to Florida and 

 the gulf states. 



By far the greater part of the orchids grow 

 in hot humid regions, where they are found 

 almost exclusively growing on trees, or epi- 

 phytic. The terrestrial species in the tropics 

 are relatively few. The epiphytes usually 

 have thick fleshy leaves, and these and their 

 thick stems serve as storage organs, for their 

 water supply is precarious. While it is true 

 that most orchids like humid conditions, this 

 is not always the case. During an exploration 

 of the Inaguas, which are extremely xero- 

 phytic, great masses of epidendrons were 

 found growing on the bases of the small 

 shrubs or trees, or on the hot limestone rock; 

 and to emphasize this desert condition, was a 

 species of Agave growing among them. They 

 seemed to flourish, for the pseudobulbs were 

 strong and vigorous. 



Nearly all tropical orchids are epiphytic, 

 while in temperate regions they are terrestrial, 

 the soil around their roots protecting them 

 from the extreme cold of winter. As a rule 

 terrestrial orchids have thin leaves, for their 



