568 



BOTANY 



PART II 



Family Ericaceae. — Flowers hypogynous or epigynous ; corolla 

 usually sympetalous ; stamens free ; anthers opening by pores or 

 short slits; ovary with completely separated loculi; placentae 

 not greatly thickened. Seeds with segmented 

 embryo (Figs. 545-547). 



The anthers of many plants of this family 

 have horn-like appendages (Fig. 547) ; the 

 whole order is therefore sometimes inappro- 

 priately named Bicornes. At their upper 

 extremities the thecse are usually free and 

 • divergent. The pollen-grains adhere in tetrads. 

 The fruit is a capsule, berry, or drupe, con- 

 of taining very small seeds with abundant endo- 

 sperm. As regards the vegetative parts, the 

 Ericaceae are typical of the order. 



Fig. 545. — Floral diagram 

 Vaccinixtm (Ericaceae). 



Sub-Families.. — (1) Rhododendroideae. Flowers hypogynous ; corolla fugacious ; 

 anthers without appendages ; septicidal capsules. Ledum, Rhododendron, Azalea, 

 etc. (2) Arbutoideae. Flowers hypo, 

 gynous ; corolla fugacious ; anthers 

 mostly appendiculate ; locucidal capsules 

 or succulent fruits. Andromeda, Arcto- 

 staphylos, etc. (3) Ericoideae. Flowers 

 hypogynous ; corolla persistent ; anthers 

 mostly appendiculate ; fruit a capsule. 

 Oalluna, calyx longer than the corolla ; 

 capsules septicidal. Erica, calyx shorter 

 than the corolla ; capsules locucidal. 

 (4) Vaccinioideae. Flowers epigynous ; 

 fruit a berry. Vaccinium, etc. 



Geographical Distribution. —The 

 plants included in this family are found 

 widely distributed over the whole earth. 

 Species of Ericoideae known as Heather, 

 Calluna vulgaris (Fig. 546), and different 

 species of Erica, cover wide stretches 

 of dry ground (heaths) in Central and 

 Western Europe with a thick bed of 

 vegetation. 



The various species of Erica, frequently 

 cultivated as pot-plants, are mostly from 

 Southern Africa, where this genus is 

 very largely represented and exhibits a 

 wonderful richness of colour. 



Poisonous. — The species of Rhodo- 

 dendron and Azalea contain toxic prin- 

 ciples in all their organs. The incautious use of Ledum palustre (Herba Rosmarini 

 silvestris) has often had fatal consequences. It is a small shrub with umbels of 

 white flowers and linear leaves covered on the under side with rusty brown hairs. 



Officinal.— Arctostaphylos Uva ursi, the Bearberry (Fig. 547), a small ever- 



Fni. 546. — Calluna vulgaris. 1, Flowering 

 branch ; 2, flower ; 3, flower cut through 

 longitudinally ; 4, fruit after dehiscence ; 5, 

 floral diagram. (After Wossidlo.) 



