| 1a. Plants without green color; leafless or with scale leaves only [— 2.] | |
| 1b. Plants with green leaves [— 4.] | |
| 2a. Flowers solitary (1-2 dm. high; summer) | Indian Pipe, Monotropa uniflora. |
| 2b. Flowers in clusters [— 3.] | |
| 3a. Petals united into a bell-shape corolla (3-9 dm. high; summer) | Pine Drops, Pterospora andromedea. |
| 3b. Petals all separate (1-3 dm. high; summer) | Beech Drops, Monotropa hypopitys. |
| 4a. Leaves all basal; herbaceous plants with terminal racemes (1-4
dm. high; summer) (Shin-leaf) [— 5.] | |
| 4b. Stem-leaves present [— 12.] | |
| 5a. Style straight [— 6.] | |
| 5b. Style bent near the apex [— 8.] | |
| 6a. Racemes one-sided, the flowers all turned in one direction
(flowers white or greenish-white) [— 7.] | |
| 6b. Raceme regular, the flowers not all pointing in the same
direction (flowers white or pink) | Shin-leaf, Pyrola minor. |
| 7a. Flowers numerous in each raceme | Shin-leaf, Pyrola secunda. |
| 7b. Flowers only 3-7 in each raceme | Shin-leaf, Pyrola seconda var. obtusata. |
| 8a. Flowers pink or purple [— 9.] | |
| 8b. Flowers white or greenish [— 10.] | |
| 9a. Leaves cordate at base | Shin-leaf, Pyrola asarifolia. |
| 9b. Leaves rounded at base, not cordate | Shin-leaf, Pyrola asarifolia var. incarnata. |
| 10a. Leaves shining on the upper side; sepals one-third as long as
the petals | Shin-leaf, Pyrola americana. |
| 10b. Leaves dull on the upper side; sepals one-fourth as long as
the petals, or a little shorter [— 11.] | |
| 11a. Leaf-blades mostly shorter than their petioles, thick and firm | Shin-leaf, Pyrola chlorantha. |
| 11b. Leaf-blades thin, usually longer than their petioles | Shin-leaf, Pyrola elliptica. |
| 12a. Petals nearly or quite separate from each other [— 13.] | |
| 12b. Petals united into a gamopetalous corolla, the tube of which
is as long as or longer than the lobes [— 18.] | |
| 13a. Leaves opposite or whorled; stems herbaceous or nearly so (summer)
[— 14.] | |
| 13b. Leaves alternate; stems shrubby (early summer) [— 16.] | |
| 14a. Flowers solitary; leaves broadly ovate to nearly circular (1
dm. high; flower white) | One-flowered Wintergreen, Moneses uniflora. |
| 14b. Flowers in clusters; leaves narrow (stems trailing, 1-3 dm.
high; flowers white or pinkish) [— 15.] | |
| 15a. Leaves broadest above the middle, green | Prince's Pine, Chimaphila umbellata. |
| 15b. Leaves broadest below the middle, spotted with white | Spotted Wintergreen, Chimaphila maculata. |
| 16a. Leaves 2-5 cm. long, densely woolly beneath (5-10 dm. high;
flowers white) | Labrador Tea, Ledum groenlandicum. |
| 16b. Leaves 1-2 cm. long, pale beneath but not wholly (creeping;
flowers pink) (Cranberry) [— 17.] | |
| 17a. Leaves acute | Cranberry, Vaccinium oxycoccos. |
| 17b. Leaves obtuse | Cranberry, Vaccinium macrocarpon. |
| 18a. Leaves opposite or whorled; corolla saucer-shape (shrubs 3-8
dm. high; flowers purple, summer) [— 19.] | |
| 18b. Leaves alternate; corolla bell-shape or salver-form [— 20.] | |
| 19a. Branches and twigs cylindrical, not angled | Sheep Laurel, Kalmia angustifolia. |
| 19b. Branches and twigs with 2 sharp angles | Swamp Laurel, Kalmia polifolia. |
| 20a. Plants prostrate, or with a few ascending branches only
(flowers white or pink) [— 21.] | |
| 20b. Plants erect or ascending [— 23.] | |
| 21a. Flowers 10-20 mm. long, very fragrant (early spring) | Trailing Arbutus, Epigaea repens. |
| 21b. Flowers 4-5 mm. long (late spring) [— 22.] | |
| 22a. Leaves spatulate, broadest beyond the middle | Bearberry, Arctostaphylos uva-ursi. |
| 22b. Leaves oval, broadest at the middle | Snowberry, Chiogenes hispidula. |
| 23a. Leaves linear, white beneath, their margins strongly revolute
(shrub 3-8 dm. high; flowers white, late spring) | Bog Rosemary, Andromeda glaucophylla. |
| 23b. Leaves oblong, scurfy beneath with rusty scales (bog shrub 4-10 dm.
high; flowers white, in spring) | Leatherleaf, Chamaedaphne calyculata. |
| 23c. Leaves smooth, pubescent, or resinous beneath, but not scurfy nor
white [— 24.] | |
| 24a. Low shrubs 10-15 cm. high, erect from a creeping rootstock;
leaves with the taste of wintergreen (flowers white or pink,
summer) | Wintergreen, Gaultheria procumbens. |
| 24b. Bushy shrubs 3-8 dm. high; leaves dotted beneath with
yellowish resinous dots; ovary 10-celled (flowers greenish-pink,
spring) | Huckleberry, Gaylussacia baccata. |
| 24c. Shrubs 1 dm. to 3 m. high; leaves not resinous-dotted beneath;
ovary 5-celled (flowers white or greenish-pink, spring or early
summer) [— 25.] | |
| 25a. Corolla bell-shape, the stamens projecting beyond it (5-15 dm.
high) | Deerberry, Vaccinium stamineum. |
| 25b. Corolla cylindrical or urn-shape, the stamens not projecting [— 26.] | |
| 26a. Filaments hairy (Blueberry) [— 27.] | |
| 26b. Filaments glabrous (Bilberry) [— 32.] | |
| 27a. Low bushy shrubs, usually less than 5 dm. and never more than 1 m.
high [— 28.] | |
| 27b. Tall erect shrubs, 1-4 m. high [— 31.] | |
| 28a. Foliage pubescent | Blueberry, Vaccinium canadense. |
| 28b. Foliage glabrous [— 29.] | |
| 29a. Leaves pale-green and glaucous, entire or nearly so | Blueberry, Vaccinium vacillans. |
| 29b. Leaves bright-green, distinctly serrulate [— 30.] | |
| 30a. Fruit blue | Blueberry, Vaccinium pennsylvanicum. |
| 30b. Fruit black | Blueberry, Vaccinium pennsylvanicum var. nigrum. |
| 31a. Leaves downy beneath; fruit black | Blueberry, Vaccinium atrococcum. |
| 31b. Leaves smooth or minutely pubescent beneath; fruit blue | Blueberry, Vaccinium corymbosum. |
| 32a. Full-grown leaves less than 2.5 cm. long; low much-branched
shrubs, mostly less than 5 dm. high [— 33.] | |
| 32b. Full-grown leaves more than 2.5 cm. long; shrubs usually a
meter high or more [— 34.] | |
| 33a. Leaves entire; petals usually 4. | Bilberry, Vaccinium uliginosum. |
| 33b. Leaves finely serrulate; petals 5 | Bilberry, Vaccinium caespitosum. |
| 34a. Leaves serrulate, green beneath, acute; corolla globular | Bilberry, Vaccinium membranaceum. |
| 34b. Leaves entire, pale beneath, obtuse; corolla ovoid | Bilberry, Vaccinium ovalifolium. |
Herbs, with alternate or opposite simple leaves and regular flowers; petals more or less united; stamens attached one in front of each petal; ovary 1-celled with 1 style.
| 1a. Leaves all basal; flowers on leafless stalks [— 2.] | |
| 1b. Stem-leaves present [— 5.] | |
| 2a. Flowers nodding, the petals reflexed (3-6 dm. high; flowers
showy, white or pink, in spring) | Shooting Star, Dodecatheon meadia. |
| 2b. Flowers erect or spreading; petals not reflexed [— 3.] | |
| 3a. Corolla not longer than the calyx; flowers small and inconspicuous
(1 dm. high; flowers white or pink, spring) | Androsace, Androsace occidentalis. |
| 3b. Corolla conspicuous, much longer than the calyx (flowers pink or
purple, summer) (Primrose) [— 4.] | |
| 4a. Leaves white-mealy beneath (1-4 dm. high) | Primrose, Primula farinosa. |
| 4b. Leaves green beneath (2 dm. high or less) | Primrose, Primula mistassinica. |
| 5a. All the stem-leaves in one whorl just below the flower-cluster [— 6.] | |
| 5b. Stem-leaves several or many, scattered over the stem [— 7.] | |
| 6a. Stem-leaves about 1 cm. long — 3a. | |
| 6b. Stem-leaves 5-10 cm. long | Star Flower, Trientalis americana. |
| 7a. Flowers red, blue, or white (summer) [— 8.] | |
| 7b. Flowers yellow (summer) [— 9.] | |
| 8a. Leaves opposite; flowers axillary (stems spreading, 1-4 dm.
long; flowers blue or red) | Pimpernel, Anagallis arvensis. |
| 8b. Leaves alternate; flowers racemose (1-4 dm. high; flowers
minute, white) | Water Pimpernel, Samolus floribundus. |
| 9a. Stem creeping | Moneywort, Lysimachia nummularia. |
| 9b. Stem erect (Loosestrife) [— 10.] | |
| 10a. Flowers in dense spike-like racemes (3-8 dm. high) | Loosestrife, Lysimachia thyrsiflora. |
| 10b. Flowers axillary or racemose (3-9 dm. high) [— 11.] | |
| 11a. Corolla dotted or streaked with purple or brown; leaves punctate
with dark spots [— 12.] | |
| 11b. Corolla plain yellow; leaves not dark-dotted [— 14.] | |
| 12a. Flowers in racemes [— 13.] | |
| 12b. Flowers all axillary | Loosestrife, Lysimachia quadrifolia. |
| 13a. Flowers all in racemes; leaves opposite or some of them alternate | Loosestrife, Lysimachia terrestris. |
| 13b. The lowest flowers axillary; leaves opposite or whorled | Loosestrife, Lysimachia producta. |
| 14a. Leaves ovate, on slender ciliate petioles | Loosestrife, Steironema ciliatum. |
| 14b. Leaves lanceolate, sessile or short-petioled, pinnately veined | Loosestrife, Steironema lanceolatum. |
| 14c. Leaves linear, with one mid-vein | Loosestrife, Steironema quadriflorum. |
Trees or shrubs, with opposite leaves and regular flowers; sepals 4, or calyx none; petals 4, united, or none; stamens usually 2; ovary 2-celled, superior.
Herbs, with opposite or basal, entire, usually simple leaves and regular flowers; sepals, petals, and stamens equal in number, 4-12; ovary superior, 1-celled.
| 1a. Leaves reduced to small scales (1-4 dm. high; flowers small,
greenish-yellow, in summer) | Bartonia, Bartonia virginica. |
| 1b. Leaves rounded, floating (flowers white, summer) | Floating Heart, Nymphoides lacunosum. |
| 1c. Leaves compound (2-4 dm. high; flowers white or bluish, early
summer) | Buckbean, Menyanthes trifoliata. |
| 1d. Leaves simple, whorled (1-2 m. high; flowers yellowish-white,
summer) | American Columbo, Frasera caroliniensis. |
| 1e. Leaves simple, opposite [— 2.] | |
| 2a. Corolla rotate, with spreading lobes, 2-4 cm. broad, pink (5-8 dm.
high; summer) | Rose Pink, Sabbatia angularis. |
| 2b. Corolla bell-shape, each petal with a spur at the base,
purplish or white, and not over 1 cm. long (1-4 dm. high; summer) | Spurred Gentian, Halenia deflexa. |
| 2c. Corolla bell-shape, tubular, funnel-form, or salver-form, not
spurred [— 3.] | |
| 3a. Corolla-lobes fringed (flowers bright-blue) (Fringed Gentian) [— 4.] | |
| 3b. Corolla-lobes entire [— 5.] | |
| 4a. Leaves lanceolate (2-8 dm. high; autumn) | Fringed Gentian, Gentiana crinita. |
| 4b. Leaves linear (1-4 dm. high; late summer) | Fringed Gentian, Gentiana procera. |
| 5a. Corolla 2 cm. long or a little less [— 6.] | |
| 5b. Corolla 2.5-5 cm. long (late summer and autumn) (Gentian) [— 7.] | |
| 6a. Upper leaves linear or narrowly lanceolate (2-4 dm. high;
flowers pink-purple, late summer) | Centaury, Centaurium umbellatum. |
| 6b. Upper leaves ovate, with several principal veins (1-5 dm. high;
flowers blue, late summer and autumn) | Gentian, Gentiana quinquefolia. |
| 7a. Calyx-lobes rough or ciliate at the margin (flowers blue, or rarely
white) [— 8.] | |
| 7b. Calyx-lobes smooth (2-8 dm. high) [— 10.] | |
| 8a. Corolla-lobes spreading; leaves narrowly lanceolate,
indistinctly veined (2-5 dm. high) | Gentian, Gentiana puberula. |
| 8b. Corolla-lobes erect or incurved; leaves ovate to
ovate-lanceolate, with 3-7 principal veins (3-6 dm. high) [— 9.] | |
| 9a. Calyx-lobes equaling or exceeding the calyx-tube | Gentian, Gentiana saponaria. |
| 9b. Calyx-lobes shorter than the calyx-tube | Gentian, Gentiana andrewsii. |
| 10a. Leaves ovate or ovate-lanceolate, somewhat cordate at base
(flowers greenish-white or yellowish-white) | Gentian, Gentiana flavida. |
| 10b. Leaves narrowly lanceolate or nearly linear, not cordate
(flowers blue) | Gentian, Gentiana linearis. |