TILIACEAE, the Linden Family

Trees, with alternate, simple, palmately veined leaves, and cl.u.s.ters 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 =Ba.s.swood, 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 p.u.b.escent 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 proc.u.mbent, 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 cl.u.s.ter --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, Hyperic.u.m kalmianum.=

2b. Styles 3 =St. John's-wort, Hyperic.u.m prolific.u.m.=

3a. Flowers pinkish, 15 mm. broad (3-5 dm. high, in swamps) =Marsh St. John's-wort, Hyperic.u.m virginic.u.m.=

3b. Flowers yellow --4.

4a. Flowers about 4 cm. wide; princ.i.p.al leaves 5-10 cm. long (7-15 dm. tall) =St. John's-wort, Hyperic.u.m 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, Hyperic.u.m elliptic.u.m.=

6a. Flowers 20-25 mm. wide; leaves of an oblong type, broadest near the middle =St. John's-wort, Hyperic.u.m perforatum.=

6b. Flowers 10-15 mm. wide; leaves of an ovate type, broadest below the middle =St. John's-wort, Hyperic.u.m punctatum.=

7a. Leaves minute, subulate, 1-3 mm. long =Pineweed, Hyperic.u.m gentianoides.=

7b. Leaves linear, with 1-3 princ.i.p.al veins, broadest near or above the middle =St. John's-wort, Hyperic.u.m canadense.=