520 THE FERTILISATION OF FLOWERS. [PART Ill. 
Orv. HLHAGNE LL. 
Lleagnus angustifolia, L., is visited by Apis mellifica, L. %, 
and Syritta pipiens (Syrphidz) (590, IL). 
Orv. SANTALACEH. 
Thesium alpinum, L., is homogamous (609, fig. 154). 
Thesium pratense, Ehrh., is visited by the hive-bee (590, IL.).: 
Orv. HUPHORBIACEL. 
The regular branching and the order of succession of the 
flowers in Luphorbia helioscopia has been thoroughly described by 
Delpino. He states that Euphorbiacez are fertilised by Diptera 
(178, 360). 
This, however, is not altogether correct. Very many short- 
lipped insects (flies, beetles, Hymenoptera) resort to the freely 
exposed honey and aid in the work of cross-fertilisation. Where 
Euphorbia is growing in abundance even bees resort to it. I 
have found upon £#. Cyparissias in Low Germany :—Diptera, 4; 
Coleoptera, 8; Hemiptera, 3; Hymenoptera, 10 (Apide, 4) ; Lepi- 
doptera, 1 (590, 11.). On the same plant I have found on the 
Alps :—21 flies; 1 beetle; 4 Hymenoptera, of which none were 
bees; and 3 Lepidoptera (609). 
Euphorbia (Poinsettia) pulcherrima has scarlet bracts, and a 
large nectary in each (726). 
A Brazilian species of Dalechampia, according to-Fritz Miiller, 
attracts the insects which cross-fertilise it by means of a colourless 
resin secreted in special glands. This is collected by the insects 
(bees), and used in nest-building (597). 
Orv. URTICACE 2. 
Tribe Urticec. 
The plants of this tribe are anemophilous ; the stamens explode 
when the flower opens, scattering the pollen (178). 
Parietaria has proterogynous flowers (351). 
1 Lists of visitors to the following Euphorbiacee are given in No. 590, II. :— 
Euphorbia Esula, L., E. Gerardiana, Jacq., Z. peplus, L., £. helioscopia, L., Buus 
sempervirens, Li. 
