^58 



A NGIOSPERMAE—DICO TYLEDONES 



Sprengel, humble-bees. Knuth, 3 humble-bees, all skg. — i. Bombus agrorum 

 i^. §; 2. E. lapidarius Z. 5 ; 3- B. terrester L. J. Herm. Miiller, the small bee 

 Halictus cylindricus F. 5, po-dvg. Scott-Elliot (Dumfriesshire), a humble-bee 

 ('Flora of Dumfriesshire,' p. 124). 



2036. H. albus L. (Knuth, ' Bliitenbiol. Beob. a. d. Ins. Capri,' p. 1 1 ; 

 Comes, ' Ult. stud.') — In this species the yellowish-white corolla projects for 2 cm. 

 from the villous sticky calyx, which is 1-5 cm. long. The stigma is receptive when 

 the flower opens, at which time the anthers of uppermost five stamens dehisce 

 and pollinate it. The remaining stamens develop successively, and in doing so 

 approximate themselves to the stigma. Automatic self-pollination is therefore 

 inevitable, and Comes states that it is effective. 



634. Petunia Juss. 



2037. P- violacea Lindl. — Darwin describes this species as self-sterile. 



2038. P. nyctaginifolia Juss. (Comes, ' Ult. stud.') — Comes states that this 

 species is infertile if insect-visits fail. 



635. Nicotiana L. 



Protogynous or homogamous flowers belonging to class C or L : with nectar 

 secreted by the base of the ovary, and stored in the corolla-tube. 



2039. N. Tabacum L. (Kirchner, 'Flora v. Stuttgart,' pp. 572-3; Knuth, 



pecies the corolla is 50-70 mm. long: its 

 upper part is bell - shaped, 



' Bloemenbiol. Bijdragen.') — In thi 



A 





with a throat 10 mm. in dia- 

 meter, and rose-coloured with 

 a darker middle line on each 

 of the expanded lobes. The 

 corolla-tube is about 30 mm. 

 long and 5 mm. broad. A 

 considerable part of it is filled 

 with the abundant nectar. The 

 lower parts of the filaments are 

 fused with the corolla-tube, and 

 these parts are covered with 

 soft hairs. 



When the flower opens 

 the stigma is mature, while the 

 anthers either dehisce simul- 

 taneously, or later, according 

 to the variet}'. The relative 

 length of stamens and style 

 also difl'ers in different varieties. 

 One of the five anthers is always situated below the stigma, and at a tolerably lower 

 level ; while the other four are either all at the same height as the stigma (or one 

 somewhat lower) or two are higher and two at the same level. 



I'IG. 2i^. Nicotiana I'abacum^ L. (from nature). 

 Irom tliL side. B, Do., partly dissected. 



A. Flower seen 



