294 ANGIOSPERMAE—DICOTYLEDONES 



the tube is filled to a depth of 2-3 mm. with the secretion, a humble-bee with a 

 proboscis 10 mm. long can just reach it, but not suck it all. Warnstorf describes the 

 pollen-grains as of a beautiful yellow colour, ellipsoidal, very delicately tuberculate, 

 about 56 fx. long and 28 ya broad. 



A.xell says that self-pollination is effective. 



Schulz observed perforated flowers. 



Visitors. — The following were recorded by the observers, and for the localities 

 stated. — 



Knuth, 2 humble-bees, skg. — Bombus hortorum L. (proboscis 19-21 mm.), and 

 B. agrorum F. 5 (prob. 15 mm.). Schulz (Bozen), the former humble-bee, and the 

 hawk-moth Macroglossa stellatarum Z., skg. legitimately. Alfken (Bremen), 3 humble- 

 bees, skg. — I. Bombus hortorum Z. 5; 2. B. ruderatus F. •}; 3. B. terrester Z. j. 



2327. G. pubescens Bess. (=G. Tetrahit Z., according to the Index Kewensis). 

 (Schulz, 'Beitrage,' II, p. 197.) — In this species Schulz observed occasional female 

 flowers, distributed gynomonoeciously, as well as feebly protandrous hermaphrodite 



725. Stachys L. 



Usually protandrous, more rarely homogaraous bee flowers. Nectar is almost 

 always secreted (but not in S. arvensis Z., according to Kirchner), as usual, by the 

 base of the ovary ; it is stored in the smooth, lowest part of the corolla-tube. The 

 upper lip not only shelters the anthers and stigma in bad weather, but also protects 

 the nectar from rain. A circlet of hairs inside the corolla-tube just above the base 

 also serves this purpose, and keeps away unbidden guests, such as flies and so forth. 

 The lower lip again forms a convenient platform ; it is generally provided with a 

 nectar-guide. 



2328. S. sylvatica L. (Sprengel, ' Entd. Geh.,' p. 307 ; Herm. Miiller, 

 ' Fertilisation,' pp. 486-7, ' Weit. Beob.,' Ill, p. 48 ; MacLeod, Bot. Jaarb. Dodonaea, 

 Ghent, V, 1893, pp. 272-3; Schulz, ' Beitrage,' II ; Kerner, 'Nat. Hist. PI.,' Eng. 

 Ed. I, II, p. 356; Loew, 'Bliitenbiol. Floristik,' p. 395; Knuth, ' Blutenbiol. 

 Herbstbeob.' ; Warnstorf, Verb. bot. Ver., Berlin, xxxviii, 1896; Kirchner, 'Flora v. 

 Stuttgart/ pp. 625-6.) — In this species the large, three-lobed lower lip of the red 

 flower possesses a purple and white design serving as a nectar-guide. The upper lip 

 is somewhat small, but it covers the anthers and stigma as the flower is almost 

 horizontal. The corolla-tube is lo-ii mm. long, its lowest 2-3 mm. being filled 

 with nectar. The flowers are protandrous. At first the tip of the style, with almost 

 apposed branches, is situated behind the anthers, which have dehisced downwards. 

 Later on it bends down under the anthers, at the same time opening its branches 

 widely. When visited by a humble-bee, therefore, cross-pollination is ensured. The 

 stigma of older flowers is dusted with pollen from younger ones. If insect-visits fail, 

 automatic self-pollination is brought about, the stigmatic branches sliding gradually 

 between the anthers, which are still covered with pollen. Kerner says that it is 

 effected by the two stigmatic branches bending downwards until they touch the 

 anthers. Warnstorf describes the pollen-grains as white in colour, ellipsoidal, bent, 

 with small tubercles, up to 43 [i long and 20-25 M broad. 



The flowers are frequently perforated by short-tongued humble-bees. 



