Shrubs, perennial herbs, or trees, with simple exstipulate leaves, and mostly perfect, gamopetalous or polypetalous flowers. Calyx inferior, free from the ovary, 4-5-parted or 4-5-cleft, mostly persistent. Corolla regular, or rarely somewhat 2-lipped and irregular, usually 4-5-toothed, -lobed or -parted. Stamens hypogynous, usually as many or twice as many as the corolla-lobes, teeth or petals; filaments mostly separate; anthers 2-celled, attached to the filaments by the back or base, the sacs often prolonged upwardly into tubes, dehiscent by terminal pores or chinks, or longitudinally, often awned. Disk crenate, lobed, or none. Ovary 2-5-celled; style elongated or short; stigma peltate or capitate; ovules usually numerous, anatropous. Fruit a capsule, berry or drupe. Seeds usually numerous and minute, or sometimes only 1 in each cavity; endosperm fleshy; embryo central; cotyledons short; radicle terete.

About 60 genera and 1100 species, of very wide geographic distribution.

*Fruit a septicidal capsule; corolla deciduous; anthers unappendaged. (Rhodo- DENDREAE.)

Corolla of separate petals; capsule dehiscent from the base.

1.

Ledum.

Corolla gamopetalous (polypetalous in no. 6); capsule dehiscent from the apex.

Corolla somewhat irregular (except in no. 5); seeds flat, winged.

Corolla funnelform to campanulate; stamens exserted.

Corolla funnelform, slightly 2-lipped; leaves deciduous.

2.

Azalea.

Corolla 2-lipped, lower lip divided to the base; leaves deciduous.

2.

Rhodora.

Corolla campanulate; leaves evergreen.

4.

Rhododendron.

Corolla urn-shaped; stamens not exserted.

5.

Menziesia.

Corolla regular; seeds angled, or rounded.

Corolla polypetalous.

6.

Dendrium.

Corolla gamopetalous.

Stamens 5; capsule 2-3-celled.

7.

Chamaecistus.

Stamens 10; capsule 5-celled.

Corolla saucer-shaped, 10-saccate.

Calyx-segments persistent; corolla-lobes rounded.

8.

Kalmia.

Calyx-segments deciduous; corolla-lobes acute.

9.

Kalmiella.

Corolla ovoid.

10.

Phyllodoce.

**Fruit a loculicidal capsule (marginally septicidal in No. 21), berry or drupe; corolla deciduous; anthers often awned.

† Fruit a dry capsule {fleshy in no. 21); calyx not accrescent, mostly small. (Andro- MEDEAE.)

‡ Corolla campanulate, cylindric, urceolate or subglobose; anthers opening by terminal pores or chinks.

Low heath-like shrubs with small subulate leaves; corolla campanulate.

Peduncles lateral; corolla 5-lobed.

11.

Cassiope.

Peduncles terminal; corolla 5-cleft.

12.

Harrimanella.

Shrubs or trees, with linear to broadly oval leaves; corolla urceolate to cylindric or subglobose.

Anther-sacs opening only at the top; shrubs; capsule oblong, ovoid, obovoid, or depressed-globose.

Capsule dehiscent into 2 layers, the outer 5-valved, the inner 10-valved; anthers awnless.

13.

Chamaedaphne.

Capsule simply 5-valved.

Sepals or calyx-lobes imbricated, at least in the bud.

Leaves evergreen; bracts persistent; anthers awnless.

14.

LeucothoŰ.

Leaves and bracts deciduous; anther-sacs 1- or 2-awnedi

15.

Eubotrys.

Sepals or calyx-lobes valvate.

Anther-sacs awned; sutures of the capsule not thickened.

Seeds smooth and shining; awns of the anther-sacs ascending; narrow-leaved

bog shrubs.

16.

Andromeda.

Seeds with a loose cellular coat; awns of the anther-sacs deflexed; broad-

leaved shrubs.

17.

Pieris.

Anther-sacs awnless; sutures of the capsule thickened.

Filaments appendaged; glabrous shrubs.

18.

Neopieris.

Filaments not appendaged; pubescent or lepidote shrubs

19.

Xolisma.

Anther-sacs opening by long chinks; tree; capsule ovoid-pyramidal; calyx-lobes valvate.

20.

Oxydendrum.

‡‡ Corolla salverform; anthers longitudinally dehiscent; prostrate shrub. (Epigaeae)

21.

Epigaea.

‡‡ Fruit a drupe, or a capsule enclosed by the fleshy accrescent calyx.

Fruit consisting of the fleshy calyx surrounding the capsule. (Gaultherieae.)

22.

Gaultheria.

Fruit a drupe with 4 or 5 nutlets. (Arbuteae.)

Nutlets coalescent; leaves persistent.

23.

Uva-Ursi.

Nutlets separate; leaves deciduous.

24.

Mairania.

*** Fruit a septicidal capsule; corolla withering-persistent; anthers appendaged. (Eri-

ceae.)

25.

Calluna.