Robertson — Flowers and qi nsects — Labiate. 119 
forced apart. This leaves the passage into the tube between 
the infolded lateral lobes and the lower one. 
The anthers are approximated in pairs under the upper lip, 
the stigma occupying the interval between them. The fore- 
most pair of anthers have only one cell, which is turned 
towards the receptacle. The outer cell is aborted, and the 
anther is turned so that the pollen-bearing cell is concealed. 
The aborted cell is bearded. When a bee enters, it strikes 
this anther and turns its face even further out of position for 
pollen contact, but when it withdraws, if it touches the 
beard, the anther is rotated downwards so as to bring the 
pollen surface in contact with the bee’s body. This mechanism 
prevents the bee from carrying pollen back from the anthers 
to the stigma of the same flower. Consequently, if the bee 
enters with pollen from another flower, it will dust it upon 
the stigma before touching the pollen of the flower. 
The flowers appear homogamous and are probably self-pol- 
linated in absence of insects. They are adapted to small long- 
tongued bees, like Ceratina and Alcidamea. Butterflies are 
useless intruders, since they can drain the tubes without trans- 
ferring pollen. The plants are common and bloom from May 
20 to June 29. On 5 days, between May 19 and June 3, I 
observed as visitors: — 
Hymenoptera — Apide: (1) Ceratina dupla Say ¢'9,8., ab.; (2) Megachile 
brevis Say 9’, 8.; (3) Alcidamea producta Cr. f'9, s. and ¢. p., very ab.; 
(4) Osmia 4—dentata Cr. 9, s.; (5) O. albiventris Cr. 9, s. and c. p.; An- 
drenide: (6) Halictus pectoralis Sm. Q, s.; (7) H. ligatus Say 2, s.; (8) H. 
pilosus Sm. 9, s.; (9) H. tegularis Rob. 9, s., freq.; (10) H. praingsas Rob. 
9, 8., freq.; 
Lepidoptera — Rhopalocera: (11) Ancyloxypha numitor F., s.; (12) Pam- 
phila ee Kby., s.; (33) Pholisora catullus F., s., fre 
Diptera — Syrphide: (14) Spherophoria cylindrica Sky, f.p.; (15) Syritta 
pipiens ts i. ps 
Scutellaria canescens Nutt.— The stems are 6 to 12 dm. 
high and are terminated by a conspicuous flower-cluster formed 
by the closely collected racemes. The flower is like that of 
the preceding, but is much larger. The middle lobe of the 
upper lip is closely folded over the stamens and style, like the 
keel of Papilionacee. The flower is nearly closed, so that, 
when the bee forces an entrance, the galea is pushed upwards 
