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. |