ORCHIDEAE 



419 



attractive to insects. Darwin always found the flowers of a spike, except one or 

 two immediately below the buds, to have been robbed of their pollinia ; he also 

 noticed pollinia on the stig- 

 mas of numerous flowers, 

 but was unable to discover 

 visitors. 



834. Microstylis Nutt. 

 " Darwin states that the 

 flower mechanism is similar 

 to that of Malaxis. 



835. Cal5rpso Salisb. 

 Perhaps humble-bee 

 flowers. 



2650. C. borealis 



Salisb. (Lundstrom, Bot. 

 Centralbl., Cassel, xxxviii^ 

 1889, pp. 697-700.) The 

 flowers of this species possess 

 a vanilla-odour, and are only 

 rarely visited by insects. 

 The pollinia are discoid and 

 unstalked. 



Visitors. Lundstrom 

 (at Piteaa in Norway) once 

 observed transfer of a polli- 

 nium by a humble-bee. He 

 repeatedly failed to produce 

 ripe fruit by artificial polli- 

 nation. These are but rarely 

 set in the natural way. 



836. Stanhopea Frost. 



2651. S.tigrinaBatem. 



(Willis, 'Contrib. to the Nat. 

 Hist, of the Flower,' (2).)- 

 Cambridge Botanic Garden are self-fertile. 



Visitors. Willis (Cambridge Botanic Garden) observed the honey-bee, species 

 of Bombus, and hover-flies. 



Fig. 388. Malaxis paludosa, Sw. (after Darwin's figure, wliicli was 

 partly copied from Bauer). A. Lateral view of perfect flower, with the 

 labellum in its natural position, upwards. B. Front view of column, 

 showing the rostellnm, the pocket-like stigma, and the anterior lateral 

 portions of the clinandrum. C. Back view of do., from a flower-bud, 

 showing the anther with the included pear-shaped pollinia dimly seen, 

 and the posterior edges of the clinandrum. D. Back view of an 

 expanded flower, with the anther now contracted and shrivelled, ex- 

 posing the pollinia. E. The two pollinia, attached to a little transverse 

 mass of viscid matter, hardened by alcohol. 



-Willis states that the flowers of this species in the 



^37* Cypripedium L. 



Labellum strongly ventricose. The species of this genus are pollinated by 

 bees, flies, and perhaps also by snails. 



E e 2 



