65 
A summary 
of 
the morphology and biology of the Krieinee. 
All the Ericineæ are adapted for cross-pollination by 
insects, and some instances are known of the visits of insects 
(mostly species of humble bees) to the flowers, although these 
visits appear to occur very sparsely and rarely. All the species 
here in question, with the exception of Pirola, secrete honey. 
The honey-secreting organs surround the base of the ovary, or 
in the case of superior flowers, the base of the style. As many 
of the species have drooping flowers it is evidently a useful 
feature that several have hairs near the base of the filaments 
and of the petals which serve to retain the honey and to pre- 
vent intruders from entering. This is doubtless also the reason 
why the base of the filaments is swollen in some of the species 
(Rhododendron, Ledum, Cassiope hypnoides, Andromeda poli- 
folia, Arctostaphylos, Phyllodoce). 
All the flowers are coloured, the majority are even of a 
‘conspicuous colour. Some of them are scented (Ledum, Pirola, 
Cassiope tetragona, C.hypnoides, Arctostaphylos alpina, Vacci- 
nium uliginosum, and (according to Bessers) Phyllodoce). 
The pollen grains which, as is well-known, are always united 
into tetrads, are quite glabrous and dry; even before the buds 
open the pores at the apex of the anthers are generally formed, 
and the grains lie loosely in the air-filled pollen-sacs, even if 
they are not always dry enough to fall out easily. This is 
also the case in Denmark with Erica Tetralix and Calluna vul- 
garis. Exceptions to this are Loiseleuria, the anthers of which 
are of the usual kind, and Phyllodoce. 
The sole function of the appendages, which occur on the 
anthers of all the species which have bell-shaped and drooping 
XXXVI. 5 
