August, 19T6.] 



THE ORfTIII) WORT^D. 



205 



just beneath it. The side wings of the cokinm 

 still retaui their |mr|)lisli tmt. It is evidently 

 the most distinct and interesting variety that 

 has yet appeared, and although it would 

 hardly be correct to describe it as an albino, 

 the decisive yellow and white areas entitle it 

 to be called O. concolor luteo-album. This 

 plant has since passed into the fine collection 

 of Mr. Philip Smith, Haddon House, Ashton- 

 on-Mersey. 



O. concolor was discovered by Gardner on 

 the Organ Mountains in 1837, and sent by 

 him to the Woburn collection, where it 

 flowered in 1840. It continued to be very 

 rare until 1870, when Messrs. Veitch received 

 a consignment from Rio de Janeiro. The 

 drooping racemes of self-coloured flowers of 

 the purest yellow render this species one of 

 the most admired in the genus. Its flowering- 

 season is April and May. The best effect is 

 produced when the plants are grown in pans 

 suspended from the roof of a cool house. 



LIMESTONE. 



THE common practice of including pieces 

 of limestone among the drainage 

 material used for Cypripedium bella- 

 tulum, C. concolor and C. niveum, owes its 

 origin to the fact that this material is often 

 found adhering to the roots of these plants 

 when newly imported. Collectors have 

 described how these Orchids have been seen 

 growing luxuriantly on limestone rocks, and 

 how many of the leaves have their surface 

 whitened by a thin deposit of this material. 

 The above Cypripediums appear to benefit 

 considerably by the addition of limestone to 

 the compost, and the question arises whether 

 any other species could be the better culti- 

 vated by adopting this treatment. Many of 

 the Jamaican Orchids are to be found growing 

 on limestone rocks, which abound in the 

 island. Mr. Geo. Syme, of the Botanic 

 Garden, Jamaica, has made the following 

 interesting statement {The Garden, Vol. 

 XXII., p. 305):- 



" The probability is great that, assisted by 



the influences of the elements, the Orchifl 

 roots in some measure dissolve and assimilate 

 the fertile limestone as food. Some such 

 action as this and some such tissue-rearing 

 food supi)ly only can account for the literal 

 acres of unusually large and luxuriant plants 

 of such species as Epidendrum cochleatum 

 and Brassia maculata as I have seen growing 

 on these rocks. The first of these species, 

 when growing on trees and ordinary rocks (in 

 contradistinction to the limestone), almost 

 invariably develops two leaves to each bulb 

 or branch, so that it is a characteristic vegeta- 

 tive condition. But, curiously enough, it is 

 broken through in the case of the plants 

 growing on the limestone referred to, inas- 

 much as these generally produce three, and 

 not infrequently four, leaves to each branch. 

 Setting aside for the moment inferences of a 

 more practical kind, have we not in these 

 limestone-reared plants of E. cochleatum, with 

 their branches terminated by three or four 

 leaves instead of two, the initial, yet incipient 

 step towards the creation of a local variety?" 



Cypripedium niveum. 



