376 
ERIANTHUS 
Erianthus Michx. Gramineae (ii). 17 sp. trop. 
Erica (Tourn.) Linn. Ericaceae (iv. 9). 420 sp. Eur. (esp. Medit.) and 
S. Afr. (see order). 5 sp. occur in Brit. The two common heaths, 
E. cinerea L. and E. Tetralix L., cover great areas of moor; the 
others are rarities of Cornwall and Ireland. In habit E. resembles 
Calluna. The fir. is bell-shaped and pendulous, visited and fertilised 
mainly by bees. Honey is secreted by the disc, and insects hanging 
on to the fir. and probing for it, must shake the sta. and receive a 
shower of the loose powdery pollen from the pores in the tips of the 
anthers. In the wider mouthed sp. the anthers have horn-like pro- 
jections at the back, which ensure contact with the insect’s proboscis. 
The stigma projects beyond the sta. so as to be touched first. 
Many S. Afr. sp. are cultivated in greenhouses. E. scoparia L. is 
the common heath of S. France, &c., growing several feet high. It is 
known as Bruyere and its rootstocks furnish ‘briar’ wood pipes. 
The roots of heaths possess an endotropic mycorhiza. 
Ericaceae. Dicotyledons (Sympet. Ericales). A family of about 50 
gen. and 1350 sp. Owing to their numbers and their social habit of 
growth the E. form very characteristic 
parts of the vegetation in many portions 
of the globe. They are found in most 
parts of the world except in deserts and 
in hot damp tropical regions. The Eri- 
coideae are confined to Africa, Medit. and 
Europe, the two great masses of them 
being however separated by the Sahara, 
though sp. of Erica, &c. occur in each. 
Another peculiar phenomenon is that 
those sp. of Andromedeae with north 
circumpolar distribution (e.g. Andromeda 
polifolia) have their nearest allies in trop. 
and sub-trop. floras (see Drude in Nat. PJl. or PJianzengeog. for a full 
discussion of the interesting distribution of E. See also the genera, 
esp. Rhododendron, Vaccinium, Calluna, Erica). 
The distribution of E. on arctic moors and swamps and on dry 
moors in warmer regions (almost all of them grow in peaty soil) would 
lead us to expect the presence of xerophytic characters in them ; and 
such is indeed the case, especially in Ericoideae . The family consists 
of woody plants varying in size from small undershrubs to large shrubs 
or even trees. Two types of habit may be distinguished — that of 
Ericoideae and that of the remaining tribes. In the latter there are 
usually true winter-buds formed (e.g. Rhododendron), even though 
the leaves may last over the winter. The bud is covered with scale 
leaves, and when its elongation occurs these drop off and a gap is left 
on the stem ; the foliage leaves tend to form rosettes at the ends of the 
twigs. The leaves themselves are generally elliptical, entire or nearly 
