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 /S||v a 



visitors. 



834. Microstylis Nutt. 

 Darwin states that the 

 flower mechanism is similar 

 to that of Malaxis. 



835. Calypso 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 

 lepeatedly 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 hone}-bee, species 

 of Bombus, and hover-flies. 



Fig. 388. Malaxis paludosa. Sw. (after D.Trwin"s figure, wliicli \vas 

 partly copied from Bauer). j4. Lateral view of perfect tlower, witii tin: 

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

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

 portions of the clinandrum. 6'. Back view of do,, from a flower-l>ud, 

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

 and the posterior edges of the clinandrum, U. Back view of an 



expanded flower, with the anther now contiacted and shrivelled, ex 

 posing th(; pollinia. ZT. The two pollinia, attached to a little transverse 

 mass of viscid matter hardened bv alcohol. 



-Willis States that the flowers of this species in the 



837- Cypripedium L. 



Labeilum strongly ventricose. The species of this genus are pollinated b)- 

 bees, flies, and perhaps also by snails. 



