CHAPTER XXIX 
SEED-BEARING PLANTS (Continued) 
METACHLAMYDE^; (Sympetalae) 
417. Coalescence. We have seen above that genera 
normally having polypetalous flowers frequently furnish 
examples of the more or less complete fusion or coalescence 
of the petals. In certain entire families this fusion of 
different members of the same circle of floral organs be- 
comes the rule, giving rise to an entire group, the Sym- 
petalcB, based upon this character. Only a few of these 
families can be cited in illustration. 
418. Heath Family (Ericaceae). The heath family in 
North America is composed chiefly of shrubs, though a 
few, as, for example, Indian pipe (Monotropa) are herbs; 1 
some of the tropical genera are trees. The beautiful 
rhododendrons, azaleas, and laurels, trailing arbutus 
(first harbinger of spring in the northern states), the aro- 
matic wintergreen, and the well-known huckleberries 
(Gaylussacia), and blueberries (Vaccinium) belong here. 
The structure of an Ericaceous flower may be illustrated 
by the common mountain laurel (Kalmia latifolia), of 
the eastern states (Figs. 357 and 358). The sepals are 
united below, but parted above; the sympetalous corolla 
1 By some authors the large heath family is separated into a number of 
smaller families, e.g., Monotropaceae, Ericaceae, Vacciniaceae. In Mono- 
tropaceae, Clethraceae, and Pyrolaceae, and a few of the true heaths (Eri- 
caceae), the corolla is polypetalous. 
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