partut] § THE MECHANISMS OF FLOWERS. 333 
i 
to form one golden-yellow surface is not only of advantage to 
this plant by increasing its conspicuousness and thereby attracting 
‘more insects, but also, as in Achillea, because the insects easily 
pass without interruption over the whole surface and _ cross- 
fertilise very many florets with their feet in the shortest possible 
time. It is of especial advantage to pollen-collecting bees and 
pollen-feeding flies, letting them perform their work in the quickest 
and most convenient manner; and this advantage to the insects 
“reacts: upon the plant itself, since these pollen-seeking insects 
naturally prefer those flowers which offer them such perceptible 
/advantages. The honey is generally accessible, since the throat of 
the corolla is only 1 mm. deep. The condition of the style aids in 
the simultaneous fertilisation of many florets by a single visitor. 
It bears at its apex a capitate tuft of divergent hairs, and in the 
first stage of the flower it presses the pollen out of the anther- 
cylinder, raising it just so high that it can be swept off the surface 
of the capitulum by the insects ; afterwards in the second stage, it 
sprea(s out its two branches, set with stigmatic papille on their 
‘inner surfaces, in the same place that the pollen occupied before. 
EF - Visitors: A, Hymenoptera—(a) Apidw: (1) Apis mellifica, L. $,s.; (2) 
‘Colletes fodiens, K. ¢ 2,8. and c.p., very ab. ; (8) C. Davieseana, K. ¢ 9,8. 
and c.p., still more ab. ; (4) Halictus maculatus, Sm. g @, s. and c.p. very ab. ; 
) Andrena fulvicrus, K. ¢,s.; (6) A. denticulata, K. 9, c¢.p.; (7) Sphecodes 
gibbus, L. ¢ 9, several varieties, including ephippia, L., s., and receiving some 
| pollen upon their hairs; (6) Sphegide: (8) Dinetus pictus, F. 9 ¢, freq. ; 
' (9) Mellinus arvensis, L.; (10) Crabro sp.; (c) Vespidw: (11) Odynerus 
peta, L. ¢. B. Diptera—(a) Stratiomyide : (12) Odontomyia viridula, 
. ab, ; (6) Syrphide : (13) Eristalis arbustorum, L. ; (14) E. nemorum, L. ; 
5) Syrphus ribesii, L., all three f-p., ab. ; (16) Syritta pipiens, L., s. and f.p., 
"very freq. ; (17) Malithrontrs teeniatus, Mgn., f.p.; (c) Muscide: (18) Sar- 
| cophaga carnaria, L. C. Lepidoptera--(a) PRhopalosara’s (19) Polyommatus 
' Phiceas, L. (as late as Oct. 19) ; (20) P. dorilis, Hfn. ; (21) Vanessa Atalanta, 
| L. (as late as Sept. 27) ; (b) Noctuew : (22) Hadena didyma, Esp. g, s., by day ; 
(c) Crambina : (23) ye hte dete alls. D. Coleoptera—Cocc iethiilie’ (24) 
' Coccinella bipunctata, L. ; (25) C. quinquepunctata, L.  E. Hemiptera— (26) 
Several species of bugs. E, Neuroptera—(27) Panorpa communis, L., freq. 
See also No. 590, mI. 
235, ARTEMISIA Dractuncutus, L., is anemophilous, but Herr 
| Borgstette has seen it visited by Melanostoma mellina (Syrphide). 
—— 
Tribe Senecionidee. 
7 236. TussILaAco FARFARA, L—In centre of each capitulum are 
thirty to forty male florets, around which stand about three hundred 
