THE MECHANISMS OF FLOWERS. 369 
282. CAMPANULA PERSICIFOLIA, L, :— 
Visitors: A. Hymenoptera—Apide: (1) Prosopis hyalinata, Sm. ? ¢. 
B. Orthoptera—(2) Forficula auricularia, L., hiding in the flowers. See also 
No. 590, Il. 
Campanula canescens, Wall., and C. colorata, Wall. two East 
‘Indian species, have cleistogamic flowers (531). 
_ Specularia perfoliata, Dec.—The cleistogamic flowers, which 
were known to Linnzus, are described by H. von Mohl (531). 
 Trachelium.—When the flower expands the pollen adheres to 
the hairs of the stigma, which in the bud grows up between the 
thers; these hairs then wither and readily give up the pollen to 
a an insect-visitor. Afterwards the stigma unfolds and its papille 
“develop. Delpino observed a cabbage-white butterfly (Pieris) 
“sucking, and a bee (Halictus) collecting pollen, on the flowers 
(178, 360). 
—~-Phytewna—The structure of the flower of Phytewma resembles 
‘on the whole that of Campanula, but the pollen, as in Composite, 
‘is pushed up out of a tube by the growing style, and comes to lie 
outside the flower exactly in the spot where the stigmas after- 
wards unfold. The tube is formed by the long strap-shaped lobes 
of the corolla which cohere for a time and afterwards separate. 
- This arrangement allows of diminution in size and aggregation of the 
flowers without interfering with the certainty of cross-fertilisation. 
' I have found the blue Alpine species of Phytewma (P. hemi- 
| sphericum, L., hwmile, Schleich., orbiculare, L., Scheuchzeri, All., 
 Michelii, All., Halleri, All.) to be visited for the most part by 
umerous bees and butterflies. For instance, on P. Micheli I 
_ observed seventeen Apide (including twelve humble-bees), forty- 
two Lepidoptera, eight Diptera, one beetle (No. 609, pp. 406-413). 
a 
— -Phytewma pauerflorum, L., was found by Ricca to be visited by 
% 
| _ humble-bees on the Alps at a height of nearly 10,000 feet (665). 
283. JASIONE MONTANA, L.—The structure of the flower was 
described thoroughly and accurately by Sprengel. The flower, to 
a greater extent even than Phytcwma, has two advantages over 
Campanula, for (1) it attracts much more numerous and more 
varied insects for the sake of its honey and pollen, and (2) it 
allows the larger visitors to fertilise a greater number of stigmas 
simultaneously with pollen from other flowers, while in Campanula 
the fertilisation of each flower requires a separate visit. 
1 The following additional species of Campanula are discussed in my Alpenblumen : 
, C. pusilla, Heenk., CO. Schewchzeri, Vill., C. barbata, L., and C. thyrsoidea, L. 
BB 
