the subtending bract
=Three-seeded Mercury, Acalypha virginica.=
2b. Leaves lanceolate to oblong; flower-clusters equaling or
exceeding the subtending bract
=Three-seeded Mercury, Acalypha gracilens.=
3a. Stem and foliage glabrous --4.
3b. Stem and foliage more or less pubescent (stems prostrate or
ascending, 1-4 dm. long) --7.
4a. Erect or ascending, usually without basal branches (2-4 dm.
tall) =Spurge, Euphorbia preslii.=
4b. Prostrate or spreading, branched from the base (stems 1-4 dm.
long) --5.
5a. Leaves entire; plants of the shores of the Great Lakes
=Spurge, Euphorbia polygonifolia.=
5b. Leaves serrulate --6.
6a. Leaves broadly oblong or obovate; seeds obscurely wrinkled
=Spurge, Euphorbia serpyllifolia.=
6b. Leaves narrowly oblong; seeds with prominent transverse ridges
=Spurge, Euphorbia glyptosperma.=
7a. Seeds black =Spurge, Euphorbia hirsuta.=
7b. Seeds red --8.
8a. Leaves oblong =Spurge, Euphorbia maculata.=
8b. Leaves elliptical to obovate; involucre split down one side
=Spurge, Euphorbia humistrata.=
9a. Flowers subtended by conspicuous petal-like white appendages (part
of the involucre) (4-10 dm. tall; summer)
=Spurge, Euphorbia corollata.=
9b. Flowers not subtended by petal-like appendages --10.
10a. Stem-leaves below the inflorescence serrulate (2-5 dm. high;
summer) --11.
10b. Stem-leaves below the inflorescence entire --13.
11a. Upper leaves acute =Spurge, Euphorbia platyphylla.=
11b. Upper leaves obtuse, rounded, or notched at the apex --12.
12a. Leaves of the involucre broadly triangular-ovate, widest near
the base =Spurge, Euphorbia obtusata.=
12b. Leaves of the involucre broadly obovate to nearly circular,
widest near or above the middle
=Spurge, Euphorbia helioscopia.=
13a. Stem-leaves narrowly linear, less than 3 mm. wide (2-4 dm. high;
late spring and summer) =Cypress Spurge, Euphorbia cyparissias.=
13b. Stem-leaves narrowly oblong-spatulate, more than 5 mm. wide, and
more than 3 times as long as wide (2-6 dm. high; summer) --14.
13c. Stem-leaves obovate to nearly circular, not more than twice as long
as wide (1-4 dm. high) --15.
14a. Leaves at base of umbel narrow, resembling those on the stem
=Spurge, Euphorbia esula.=
14b. Leaves at base of umbel broad, resembling those of the
inflorescence =Spurge, Euphorbia lucida.=
15a. Upper stem-leaves distinctly narrowed at the base; introduced
species of waste places (summer) =Spurge, Euphorbia peplus.=
15b. Upper stem-leaves rounded at the sessile base; native species of
woodlands (spring and early summer) =Spurge, Euphorbia commutata.=
CALLITRICHACEAE, the Water Starwort Family
Small herbs growing in water or in mud, with opposite entire leaves and
small inconspicuous axillary flowers, with neither calyx nor corolla.
(Flowers in summer).
1a. Completely submerged; leaves all linear
=Water Starwort, Callitriche autumnalis.=
1b. Submerged leaves linear, emersed and floating leaves obovate
=Water Starwort, Callitriche palustris.=
EMPETRACEAE, the Crowberry Family
Low evergreen shrubs, with the linear leaves completely rolled into a
tube, and inconspicuous flowers without petals, in the axils of the
leaves.
One species in Michigan, 1-3 dm. high; leaves less than 1 cm. long;
flowers in summer =Crowberry, Empetrum nigrum.=
LIMNANTHACEAE, the False Mermaid Family
Low herbs with alternate compound leaves and minute axillary flowers;
sepals 3, petals 3, stamens 6.
One species in Michigan, with stems 1-3 dm. long, and flowers in late
spring =False Mermaid, Floerkea proserpinacoides.=
ANACARDIACEAE, the Cashew Family
Shrubs or small trees, with milky or resinous juice, alternate compound
leaves sometimes poisonous to the touch, and small clustered greenish or
yellowish flowers.
1a. Leaflets 7 to many (1-5 m. high) (Sumach) --2.
1b. Leaflets 3-5.
2a. Axis of the leaves wing-margined between the leaflets
=Sumach, Rhus copallina.=
2b. Axis of the leaves not margined --3.
3a. Leaflets entire =Poison Sumach, Rhus vernix.=
3b. Leaflets serrate --4.
4a. Bark of the older stems glabrous =Sumach, Rhus glabra.=
4b. Bark of the older stems densely velvety-hairy
=Sumach, Rhus typhina.=
5a. Terminal leaflet narrowed to a sessile base (5-20 dm. high)
=Sumach, Rhus canadensis.=
5b. Terminal leaflet on a definite stalk, round or acute at base (3-8
dm. high, or climbing by hold-fast roots)
=Poison Ivy, Rhus toxicodendron.=
AQUIFOLIACEAE, the Holly Family
Shrubs, with alternate simple leaves and small white or greenish
axillary flowers in late spring and early summer; sepals, petals, and
stamens each 4-6; fruit a berry.
1a. Leaves entire or nearly so, 1-3 cm. long (1-2 m. tall)
=Mountain Holly, Nemopanthus mucronata.=
1b. Leaves sharply serrate, 5-8 cm. long (2-5 m. high) (Black Alder)
--2.
2a. Leaves downy on the veins beneath; fruit red
=Black Alder, Ilex verticillata.=
2b. Leaves nearly or quite glabrous; fruit orange
=Black Alder, Ilex verticillata var. tenuifolia.=
CELASTRACEAE, the Staff Tree Family
Shrubs with simple leaves and inconspicuous flowers; sepals and petals
each 4 or 5, the stamens of the same number and attached to a disk which
fills the center of the flower; fruit showy, orange and red.
1a. Leaves alternate (climbing vine; flowers in racemes; late spring)
=Bitter-sweet, Celastrus scandens.=
1b. Leaves opposite (flowers in axillary clusters) --2.
2a. Prostrate, with short erect branches; leaves broadest above the
middle (spring) =Creeping Wahoo, Evonymus obovatus.=
2b. Tall shrub, with leaves broadest below or near the middle
(early summer) =Wahoo, Evonymus atropurpureus.=
STAPHYLEACEAE, the Bladder Nut Family
Shrubs with opposite trifoliate leaves and small axillary clusters of
white flowers in spring; sepals, petals, and stamens each 5; ovary
3-celled, ripening into a large inflated 3-celled pod.
One species in Michigan (2-5 m. high) =Bladder Nut, Staphylea trifolia.=
ACERACEAE, the Maple Family
Trees or shrubs, with opposite, lobed or compound leaves and
inconspicuous flowers; sepals about 5; petals the same number, or none;
stamens 4-12; ovary 2-lobed, ripening into a pair of winged fruits.
1a. Leaves compound (tree; flowers appearing before the leaves)
=Box Elder, Acer negundo.=
1b. Leaves simple (Maple) --2.
2a. Shrubs or small trees; leaves 3-5-lobed; the lobes with
regularly serrate margins (flowers greenish-yellow, appearing
later than the leaves) --3.
2b. Trees; leaves 3-7-lobed; margins of the lobes entire or
incised, but never regularly serrate --4.
3a. Leaves finely and sharply serrate; twigs smooth; bark conspicuously
striped with white lines =Striped Maple, Acer pennsylvanicum.=
3b. Leaves coarsely and bluntly serrate; young twigs pubescent; bark not
striped =Mountain Maple, Acer spicatum.=
4a. Angles between the leaf-lobes rounded (flowers greenish-yellow,
appearing with the leaves) --5.
4b. Angles between the leaf-lobes acute or obtuse, but not rounded
(flowers purple, red, or yellowish, appearing before the
leaves) --6.
5a. Leaves glabrous beneath, or minutely pubescent on the veins
=Sugar Maple, Acer saccharum.=
5b. Leaves downy beneath =Black Maple, Acer saccharum var. nigrum.=
6a. Middle leaf-lobe usually more than half the length of the leaf,
narrowed at its base; broken twigs with a strong odor
=Silver Maple, Acer saccharinum.=
6b. Middle leaf-lobe usually less than half the length of the leaf,
its sides parallel or broadened at the base; broken twigs
without strong odor =Red Maple, Acer rubrum.=
SAPINDACEAE, the Soapberry Family
Trees, with opposite palmately compound leaves, and showy white or
yellowish flowers in panicles in spring; sepals 5; petals 4 or 5;
stamens about 7; fruit a smooth brown nut.
1a. Leaflets 7; buds viscid; corolla of 5 petals
=Horse Chestnut, Aesculus hippocastanum.=
1b. Leaflets 5; buds smooth; corolla of 4 petals
=Buckeye, Aesculus glabra.=
BALSAMINACEAE, the Touch-me-not Family
Smooth herbs, with alternate simple leaves and showy flowers; one
petal-like sepal prolonged into a spur; fruit explosive when ripe (5-10
dm. high; summer).
1a. Flowers pale-yellow, with a few red-brown spots
=Touch-me-not, Impatiens pallida.=
1b. Flowers orange, thickly spotted with red-brown
=Touch-me-not, Impatiens biflora.=
RHAMNACEAE, the Buckthorn Family
Shrubs, with simple leaves and small flowers in axillary or terminal
clusters in early summer; sepals, petals, and stamens each 4 to 5, or
petals none.
1a. Leaves with a single mid-vein; flowers in axillary clusters,
greenish (Buckthorn) --2.
1b. Leaves with 3-5 principal veins; flowers in dense terminal clusters,
white (Red-root) --3.
2a. Lateral veins 3-4 pairs (stout shrub, frequently thorny,
escaped from cultivation) =Buckthorn, Rhamnus cathartica.=
2b. Lateral veins 6-9 pairs (1 m. high or less; in swamps and bogs)
=Buckthorn, Rhamnus alnifolia.=
3a. Leaves ovate, rounded or cordate at the base, 2-5 cm. wide or more
(4-8 dm. high) =Red-root, Ceanothus americanus.=
3b. Leaves elliptical-lanceolate, 2 cm. wide or less (3-8 dm. high)
=Red-root, Ceanothus ovatus.=
VITACEAE, the Grape Family
Shrubs, climbing by tendrils or hold-fast roots, with palmately lobed or
palmately compound leaves and small greenish flowers in panicles or
flattened clusters; petals and sepals each 4 or 5; fruit a berry.
1a. Leaves compound (summer) (Virginia Creeper) --2.
1b. Leaves simple (late spring) (Grape) --4.
2a. Branches of the tendrils chiefly ending in adhesive disks --3.
2b. Branches of the tendrils twining, or rarely with a few disks
=Virginia Creeper, Psedera vitacea.=
3a. Stem and foliage glabrous
=Virginia Creeper, Psedera quinquefolia.=
3b. Stem and foliage pubescent, at least when young
=Virginia Creeper, Psedera quinquefolia var. hirsuta.=
4a. Leaves conspicuously pubescent beneath --5.
4b. Leaves glabrous beneath when mature, or pubescent on the veins
only --6.
5a. A tendril or flower-cluster opposite each leaf
=Fox Grape, Vitis labrusca.=
5b. No tendril opposite each third leaf
=Summer Grape, Vitis aestivalis.=
6a. Pith continuous through the joints of the stem
=Fox Grape, Vitis rotundifolia.=
6b. Pith interrupted by the solid joints --7.
7a. Leaf-lobes with rounded angles between them
=Summer Grape, Vitis bicolor.=
7b. Leaf-lobes with sharp angles between them --8.
8a. Leaves coarsely toothed, unlobed or slightly 3-lobed
=Frost Grape, Vitis cordifolia.=
8b. Leaves sharply toothed, prominently lobed
=Frost Grape, Vitis vulpina.=
TILIACEAE, the Linden Family
Trees, with alternate, simple, palmately veined leaves, and clusters of
fragrant white flowers in late spring arising from the middle of a
leaf-like bract; sepals and petals each 5; stamens numerous, but united
into 5 sets.
One species in Michigan =Basswood, Tilia americana.=
MALVACEAE, the Mallow Family
Herbs with alternate leaves; sepals and petals each 5; stamens numerous,
united by their filaments to form a tube surrounding the styles; ovary
many-celled.
1a. Flowers yellow (summer and autumn) --2.
1b. Flowers pale-yellow, with a dark center (2-4 dm. high; late summer)
=Flower-of-an-hour, Hibiscus trionum.=
1c. Flowers white to red or blue, never yellow --3.
2a. Leaves broadly heart-shape (10-15 dm. tall)
=Velvet Leaf, Abutilon theophrasti.=
2b. Leaves ovate-lanceolate (2-5 dm. tall) =Sida, Sida spinosa.=
3a. Calyx subtended by 6 to many bractlets which are sometimes united at
base (summer) --4.
3b. Calyx subtended by 3 bractlets, or by none --6.
4a. Flowers 2-4 cm. wide (5-10 dm. high; flowers pink)
=Marsh Mallow, Althaea officinalis.=
4b. Flowers 7-15 cm. wide (8-15 dm. high; flowers pink to nearly
white) (Rose Mallow) --5.
5a. Leaves densely pubescent below =Rose Mallow, Hibiscus moscheutos.=
5b. Leaves glabrous =Rose Mallow, Hibiscus militaris.=
6a. Petals prominently notched at the end or reverse heart-shape
(Mallow) --7.
6b. Petals obtuse or truncate (summer) --11.
7a. Flowers 1-1.5 cm. wide --8.
7b. Flowers 2-5 cm. wide (3-8 dm. high; flowers in summer) --9.
8a. Stems procumbent, prostrate, or spreading (spring, summer, and
autumn) =Mallow, Malva rotundifolia.=
8b. Stems erect (10-15 dm. high; summer)
=Mallow, Malva verticillata.=
9a. Leaves with prominent but shallow lobes; flowers axillary
=Mallow, Malva sylvestris.=
9b. Leaves deeply lobed or cleft; flowers in the upper axils, producing
a raceme-like cluster --10.
10a. Lobes of the leaf dentate or incised =Mallow, Malva alcea.=
10b. Lobes of the leaf pinnately cleft into linear or narrowly
oblong divisions =Mallow, Malva moschata.=
11a. Flowers white (1-2 m. high) =Virginia Mallow, Sida hermaphrodita.=
11b. Flowers purple or pink (3-5 dm. high, spreading)
=Poppy Mallow, Callirhoe triangulata.=
HYPERICACEAE, the St. John's-wort Family
Herbs or shrubs, with opposite entire leaves dotted with translucent
glands; flowers usually yellow (or pink); sepals and petals each 5;
stamens 5 to many; ovary with 3-5 styles. (St. John's-wort.)
1a. Shrubs (4-8 dm. high; flowers yellow, summer) --2.
1b. Herbs (flowers in summer) --3.
2a. Styles 5 =St. John's-wort, Hypericum kalmianum.=
2b. Styles 3 =St. John's-wort, Hypericum prolificum.=
3a. Flowers pinkish, 15 mm. broad (3-5 dm. high, in swamps)
=Marsh St. John's-wort, Hypericum virginicum.=
3b. Flowers yellow --4.
4a. Flowers about 4 cm. wide; principal leaves 5-10 cm. long (7-15
dm. tall) =St. John's-wort, Hypericum ascyron.=
4b. Flowers 8-25 mm. wide; stamens 15 or more --5.
4c. Flowers 1-10 mm. wide; stamens 12 or fewer (1-6 dm. high) --7.
5a. Petals dotted with black (4-8 dm. high) --6.
5b. Petals without black dots (2-5 dm. high)
=St. John's-wort, Hypericum ellipticum.=
6a. Flowers 20-25 mm. wide; leaves of an oblong type, broadest near
the middle =St. John's-wort, Hypericum perforatum.=
6b. Flowers 10-15 mm. wide; leaves of an ovate type, broadest below
the middle =St. John's-wort, Hypericum punctatum.=
7a. Leaves minute, subulate, 1-3 mm. long
=Pineweed, Hypericum gentianoides.=
7b. Leaves linear, with 1-3 principal veins, broadest near or above the
middle =St. John's-wort, Hypericum canadense.=
7c. Leaves lanceolate, 4-6 times as long as broad, with 5-7 principal
veins =St. John's-wort, Hypericum majus.=
7d. Leaves oblong, elliptic, or ovate, 1.5-3 times as long as broad --8.
8a. Uppermost bracts linear =St. John's-wort, Hypericum mutilum.=
8b. Uppermost bracts resembling the leaves in shape, but smaller
=St. John's-wort, Hypericum boreale.=
ELATINACEAE, the Waterwort Family
Small marsh herbs, with opposite leaves without translucent dots, and
inconspicuous axillary flowers. (Stems 2-5 cm. long; flowers in summer.)
One species in Michigan =Waterwort, Elatine americana.=
CISTACEAE, the Rock-rose Family
Small herbs or shrubs, with opposite or alternate entire leaves; flowers
regular, with 5 sepals, 3 or 5 petals, and 3 to many stamens.
1a. Flowers yellow (early summer) --2.
1b. Flowers greenish or purplish, minute, in panicles (late summer)
(Pinweed) --4.
2a. Leaves crowded, closely appressed to the branches; flowers
7 mm. wide (2-4 dm. high)
=False Heather, Hudsonia tomentosa.=
2b. Leaves spreading; flowers 15-30 mm. wide (3-6 dm. high)
(Frostweed) --3.
3a. Petal-bearing flowers solitary
=Frostweed, Helianthemum canadense.=
3b. Petal-bearing flowers few, racemose
=Frostweed, Helianthemum majus.=
4a. Stem-leaves linear, 4 or more times as long as wide --5.
4b. Stem-leaves oblong or elliptical, about 3 times as long as wide
(2-6 dm. tall) --8.
5a. Plant pale with dense appressed pubescence (2-4 dm. high)
=Pinweed, Lechea stricta.=
5b. Plant green, pubescence sparse or none --6.
6a. Leaves thread-like, seldom exceeding 1 mm. in width (1-3 dm.
tall) =Pinweed, Lechea tenuifolia.=
6b. Leaves 1-5 mm. wide (2-6 dm. high) --7.
7a. Leaves on the basal shoots narrowly lanceolate
=Pinweed, Lechea intermedia.=
7b. Leaves on the basal shoots oblong-elliptic, about twice as long as
wide =Pinweed, Lechea racemulosa.=
8a. Pubescence of spreading hairs =Pinweed, Lechea villosa.=
8b. Pubescence of appressed hairs =Pinweed, Lechea minor.=
VIOLACEAE, the Violet Family
Herbs with simple, alternate or basal leaves, and conspicuous irregular
flowers with a spur (except in the first species); sepals, petals, and
stamens each 5; ovary 1-celled.
1a. Flowers regular or nearly so, greenish-white, axillary; erect plant
with leafy stem (3-5 dm. high; spring)
=Green Violet, Hybanthus concolor.=
1b. Flowers irregular, blue, yellow, or white, conspicuous (Violet) --2.
2a. Plant stemless, the flowers all on leafless stalks and the
leaves all basal (spring or early summer) --3.
2b. Stems leafy (spring and summer) --17.
3a. Petals yellow =Round-leaved Violet, Viola rotundifolia.=
3b. Petals blue, violet, or white --4.
4a. Principal leaves at time of flowering deeply lobed --5.
4b. Leaves oblong, ovate, or triangular, not narrowed to the
petiole, and frequently sharply toothed or incised near the
base --7.
4c. Leaves narrowly lanceolate, tapering to the base
=Violet, Viola lanceolata.=
4d. Leaves heart-shape or kidney-shape, not lobed --8.
5a. Lateral petals bearded --6.
5b. Lateral petals not bearded =Bird-foot Violet, Viola pedata.=
6a. Leaves divided to the base into linear segments
=Bird-foot Violet, Viola pedatifida.=
6b. Leaves irregularly divided into broader segments
=Hand-leaf Violet, Viola palmata.=
7a. Leaves ovate-oblong, pubescent =Violet, Viola fimbriatula.=
7b. Leaves triangular-lanceolate, usually somewhat dilated at base,
nearly or quite glabrous =Violet, Viola sagittata.=
8a. Flowers violet or blue (rarely white-flowered plants are found
with the typical blue-flowered ones) (Blue Violets) --9.
8b. Flowers white, the 3 lower petals marked with purple (White
Violets) --14.
9a. Lateral petals bearded --10.
9b. Lateral petals beardless =Great-spurred Violet, Viola selkirkii.=
10a. Foliage glabrous --11.
10b. Petioles and lower surface of leaves pubescent --13.
11a. Beard of the lateral petals with a knob at the tip of each hair
=Blue Violet, Viola cucullata.=
11b. Beard of the lateral petals not knobbed --12.
12a. Spurred petal hairy =Wood Violet, Viola affinis.=
12b. Spurred petal glabrous =Blue Violet, Viola papilionacea.=
13a. Spurred petal villous =Blue Violet, Viola septentrionalis.=
13b. Spurred petal glabrous, or with a few scattered hairs
=Common Blue Violet, Viola sororia.=
14a. Leaf-blade obviously pubescent --15.
14b. Leaf-blade glabrous or very nearly so --16.
15a. Lateral petals bearded =Sweet White Violet, Viola incognita.=
15b. Lateral petals not bearded =White Violet, Viola renifolia.=
16a. Leaf-blades strictly glabrous
=Sweet White Violet; Viola pallens.=
16b. Leaf-blades with some minute white hairs on the upper surface
near the base =Sweet White Violet, Viola blanda.=
17a. Stipules large and leaf-like, deeply pinnatifid and nearly or quite
as long as the petioles --18.
17b. Stipules small, inconspicuous, entire or toothed, and much shorter
than the petiole --19.
18a. Leaves serrate; flowers 1.5-2.5 cm. wide (1-3 dm. high;
flowers of various colors) =Pansy, Viola tricolor.=
18b. Upper leaves entire or nearly so; flowers about 1 cm. wide
(1-2 dm. high; flowers bluish-white)
=Wild Pansy, Viola rafinesquii.=
19a. Petals yellow (1-4 dm. high) (Yellow Violet) --20.
19b. Petals violet, blue, or white --21.
20a. Foliage villous-pubescent =Yellow Violet, Viola pubescens.=
20b. Foliage nearly or quite glabrous
=Yellow Violet, Viola scabriuscula.=
21a. Stipules entire (2-4 dm. high) =Canada Violet, Viola canadensis.=
21b. Stipules toothed --22.
22a. Lateral petals not bearded (1-2 dm. high)
=Long-spurred Violet, Viola rostrata.=
22b. Lateral petals bearded --23.
23a. Flowers white or nearly white (1-3 dm. high)
=Pale Violet, Viola striata.=
23b. Flowers blue (about 1 dm. high) --24.
24a. Leaves smooth =Dog Violet, Viola conspersa.=
24b. Leaves pubescent =Sand Violet, Viola arenaria.=
CACTACEAE, the Cactus Family
Fleshy, jointed leafless plants, armed with numerous thorns; flowers
large (5-10 cm. wide), yellow, with about 10 petals and numerous
stamens.
One species in Michigan, on the shores of Lake Michigan; flowers in
summer =Prickly Pear, Opuntia rafinesquii.=
THYMELAEACEAE, the Mezereum Family
Shrubs, with simple alternate entire leaves, and small yellowish flowers
in clusters, opening before the leaves; petals none, the sepals somewhat
petal-like.
One species in Michigan, 5-15 dm. tall, with very tough bark
=Leatherwood, Dirca palustris.=
ELAEAGNACEAE, the Oleaster Family
Shrubs, with opposite, silvery-pubescent, simple, entire leaves, and
small clusters of inconspicuous yellow flowers in spring.
One species in Michigan, 1-2 m. high
=Buffalo Berry, Shepherdia canadensis.=
LYTHRACEAE, the Loosestrife Family
Herbs or shrubs, with opposite or alternate entire leaves; receptacle
cup-shape or tubular, bearing the 5-7 petals and sepals at its margin,
and the 6-12 stamens on its inner surface; ovary superior.
1a. Stem shrubby (aquatic, stems 1-3 m. long; flowers pink, summer)
=Water Loosestrife, Decodon verticillatus.=
1b. Stem herbaceous (4-10 dm. high; flowers purple, summer) --2.
2a. Flowers solitary in the axils; leaves mostly alternate
=Loosestrife, Lythrum alatum.=
2b. Flowers in terminal panicles; leaves opposite or whorled
=Loosestrife, Lythrum salicaria.=
MELASTOMACEAE, the Melastoma Family
Herbs, with opposite leaves with 3-5 principal veins; receptacle
urn-shape, bearing 4 sepals and 4 petals at its edge; stamens 8; ovary
4-celled, superior.
One species in Michigan, 3-4 dm. high, with purple flowers in late
summer =Meadow Beauty, Rhexia virginica.=
ONAGRACEAE, the Evening Primrose Family
Herbs with opposite or alternate simple leaves and regular flowers;
sepals and petals each 4 (or 2 in one genus), stamens 8 (or 2 in one
genus), attached to the summit or inside of a tubular receptacle; ovary
2-4-celled, inferior.
1a. Aquatic plant of shallow water or muddy ground, with prostrate stem
(flowers minute, axillary; petals small or none, summer)
=Water Purslane, Ludvigia palustris.=
1b. Land plants with erect or ascending stems --2.
2a. Petals minute, greenish (3-8 dm. high; late summer)
=False Loosestrife, Ludvigia polycarpa.=
2b. Petals yellow --3.
2c. Petals white, pink, purple, or red --9.
3a. Sepals borne at the summit of the ovary (5-10 dm. high; summer)
=False Loosestrife, Ludvigia alternifolia.=
3b. Sepals borne at the summit of the slender tubular receptacle, which
is prolonged beyond the ovary --4.
4a. Stamens all equal in length (Evening Primrose) --5.
4b. The alternate stamens longer (3-8 dm. high; summer) (Sundrops)
--8.
5a. Leaves deeply dentate or pinnatifid (2-5 dm. high; early summer)
=Evening Primrose, Oenothera laciniata.=
5b. Leaves entire or undulate or finely toothed (5-12 dm. high; summer)
--6.
6a. Hairs on the stem with broad reddish bases
=Evening Primrose, Oenothera muricata.=
6b. Hairs on the stem none, or without swollen bases --7.
7a. Stem and foliage glabrous, or with sparse spreading hairs
=Evening Primrose, Oenothera biennis.=
7b. Stem and foliage densely but closely appressed-pubescent
=Evening Primrose, Oenothera rhombipetala.=
8a. Petals 5-10 mm. long =Sundrops, Oenothera pumila.=
8b. Petals 14 mm. long or more =Sundrops, Oenothera fruticosa.=
9a. Petals 2, reverse heart-shape, stamens 2 (flowers small, white,
summer) (Enchanter's Nightshade) --10.
9b. Petals 4; stamens 4 or 8 --12.
10a. Leaves rounded at the base, denticulate (3-8 dm. high; fruit
prickly) =Enchanter's Nightshade, Circaea lutetiana.=
10b. Leaves cordate at the base --11.
11a. Fruit 2-celled, bristly (2-4 dm. high)
=Enchanter's Nightshade, Circaea intermedia.=