150 PHASEOLUS MULTIFI OKUS. CHAP. V 



generations taken together was 35 * 5, and that of the three self- 

 fertilised plants of the same two generations 30*5; or as 100 

 to 86.* 



PHASEOLUS MULTIFLOKUS. 



This plant, the scarlet-runner of English gardeners and the P. 

 coccineus of Lamarck, originally came from Mexico, as I am in- 

 formed by Mr. Bentham. The flowers are so constructed that 

 hive and humble-bees, which visit them incessantly, almost always 

 alight on the left wing-petal, as they can best suck the nectar 

 from this side. Their weight and movements depress the petal, 

 and this causes the stigma to protrude from the spirally- wound 

 keel, and a brush of hairs round the stigma pushes out the pollen 

 before it. The pollen adheres to the head or proboscis of the 

 bee which is at work, and is thus placed either on the stigma 

 of the same flower, or is carried to another flower.t Several 

 years ago I covered some plants under a large net, and these 

 produced on one occasion about one-third, and on another occa- 

 sion about one-eighth, of the number of pods which the same 

 number of uncovered plants growing close alongside produced.^ 

 This lessened fertility -was not caused by any injury from the 

 net, as I moved the wing-petals of several protected flowers, in 

 the same manner as bees do, and these produced remarkably 



* We here see that both Lupi- in the ' Annals and Mag. of Nat. 

 nus luteus and pilosus seed freely Hist.' vol. ii. (4th series) Oct. 

 when insects are excluded; but 1868, p. 256. My son Francis 

 Mr. Swale, of Christchurch, in has explained ('Nature,' Jan. 8, 

 New Zealand, informs me (see 1874;, p. 189) the use of one pecu- 

 ' Gardeners' Chronicle,' 1858, p. liarity in their structure, namely, 

 828) that the garden varieties of a little vertical projection on the 

 the lupine are not there visited by single free stamen near its base, 

 any bees, and that they seed less which seems placed as if to guard 

 freely than any other introduced the entrance into the two nectar- 

 leguminous plant, with the excep- holes in the staminal sheath. 

 tion of red clover. He adds, " I He shows that this projection pre- 

 have, for amusement, during the vents the bees reaching the nectar, 

 summer, released the stamens with unless they go to the left side of 

 a pin, and a pod of seed has always the flower, and it is absolutely 

 rewarded me for my trouble, the necessary for cross-fertilisation 

 adjoining flowers not so served that they should alight on the 

 having all proved blind." I do left wing-petal, 

 not know to what species this J ' Gardeners' Chronicle,' 1857. 

 statement refers. p. 725, and more especially ibid! 



t The flowers have been de- 1858, p. 828. Also 'Annals and 



scribed by Delpino, and in an Mag. of Nat. Hist.' (3rd series) 



admirable manner by Mr. Farrer vol. ii. 1858, p. 462. 



