160 Trans. Acad. Sci. of St. Louis. 



Aesculus glabra Willd. — Coulter (12) records the fact 

 that the flowers are andromonoecious, the perfect ones 

 proterogynous. The trees are common and bear numerous 

 panicles of yellowish flowers. The two lower petals are 

 directed horizontally, lying on each side of the stamens. 

 The two upper ones are turned upwards and form a vexillum, 

 being marked by yellow blotches which serve as pathfinders. 

 These by turning reddish enable the bees to distinguish the 

 older flowers, which only serve to increase the conspicuousness 

 of the inflorescence. The stamens and stvle are declined to 

 the lower side and are curved upwards. The stamens are of 

 unequal length and the longest are exserted 10 mm. beyond 

 the tips of the lower petals. The anthers dehisce in suc- 

 cession. 



Nectar is secreted by a portion of the disc which is strongly 

 developed above and may be reached by a bee inserting its 

 proboscis above the filaments. On account of the depth of 

 the calyx tube a proboscis 10 mm. long is needed to do this 

 easily. The flowers are adapted to bumble bees, which on 

 account of the early blooming time — April 20-May 11 — 

 are represented only by the females, and by other long 

 tongues, such as Anthophora and SynlLalonia. May 4, 5 and 

 9, I saw the flowers visited by the following : — 



Apidae — (1) Bombus separatus Cr. $ ; (2) B. peunsylvanicus De G. ?, 

 freq.; (3) B. americanorum F. $, freq.; (4) B. virginicus Oliv. 9; (5) 

 Anthophora ursina Cr, $ ; (6) Synhalonia frater Cr. 9 ! (7) S. belfragei 

 Cr. (5^9, freq., in cop. — all sucking. 



On the literature of Aesculus see: — 



(1) Sprengel, Das entdeckte Geheimniss, 209-14. 1793.— (2) Hildebrand, 

 Geschlechter-vertheilung bei den Pflanzen, 11, 26. 1867.— (3) Axell, Om 

 anordningarna for de fanerogama vJixteruas befruktning, 104. 1869. AE. 

 hippocastanum, cit. (2) — (4) Ogle, The fertilization of some plants. Pop. 

 Sci. Rev. 9:54 Ja 1870.— (5) Miiller, Befruchtung der Blumen, 154-6. 1873. 

 AE. hippocastanum, riibicunda. — (6) Delpino, Ulteriori osservazioui. II. 

 2:178, 266, 268. 1875. Atti. d. Soc. Ital. d. Sci. in Milano. 16:326. 1873. 

 17:—. 1874. AE. hippocastanum, ruhimnda. — (7) Errera et Gevaert, Sur 

 la structure et les modes de f^condation des fleurs. Bull. d. Soc. roy. d. Bot. 

 Belgique 17:146. 1878. AE. hippocastanum, cit. (4).— (8) Hildebrand, 

 Die Farben der Bliithen in ihrer jetzigen variation uud friiheren Ent- 

 wickelung, 38. 1879. AE. hippocastanum, color changes. (Just 7^:110)- 

 (9) Bonnier, Les Nectaires. Ann. d. Sci. nat. Bot. VI. 8:107. f. 29 



