This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol2", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Geranium pusillum L. Sp. Pl. Ed. 2, 957. 1763.
Annual, widely branching, slender, weak, pubescent or villous, 4'-18' long. Leaves petioled, reni-form-orbicular, 1/2'-1 1/2 wide, deeply divided into 7-9 oblong, or sometimes linear-oblong, entire or 3-toothed, cuneate lobes; peduncles short, 3"-°" long, 2-flowered; pedicels 3"-12" long; sepals acute, awn-less; flowers pale-purple, 3"-s" broad; petals notched; capsule-lobes hairy, keeled, not wrinkled; beak about 5" long, canescent; seed smooth; anther-bearing stamens commonly only 5, as in Erodium.
Geranium molle L. Sp. Pl. 682. 1753.
Resembling the preceding species, but more villous, the leaves nearly orbicular in outline and not as deeply cleft, generally only to just below the middle, into 7-11 obovate or cuneate lobes, which are 3-5-toothed at the apex; flowers dark-purple, 3"-5" broad; sepals obtusish, not awned; capsule-lobes distinctly marked with transverse wrinkles; beak about 5" long, sparingly pubescent; seeds smooth or striate, not pitted, nor reticulate; anther-bearing filaments 10.
In lawns and waste places, Maine to Pennsylvania. New York, Ohio and Ontario. Also in Washington and Vancouver. Fugitive from Europe. Other English names are pigeon-foot, starlights, culverfoot. May-Sept.
3. ERŅDIUM L'Her.; Ait. Hort. Kew. 2: 414. 1789.
Herbs, generally with jointed nodes, opposite or alternate stipulate leaves, and axillary umbellate nearly regular flowers. Sepals 5, imbricated. Petals 5, hypogynous, imbricated, the 2 upper slightly smaller. Glands 5. Anther-bearing stamens 5, alternating with as many sterile filaments. Ovary 5-lobed, 5-celled, beaked by the united styles, the beak terminating in 5 stigmas; ovules 2 in each cavity. Capsule-lobes I-seeded, the styles elastically dehiscent and coiled spirally at maturity, villous-bearded on the inner side. Seeds not reticulate. [Greek, a heron, from the resemblance of the fruit to its beak and bill.]
About 60 species, widely distributed in temperate and warm regions. There are three native species in the southwest and several exotic ones have been collected on ballast at the seaports. Type species: Erodium crassifolium Soland.
Geranium cicutarium L. Sp. Pl. 680. 1753.
E. cicutarium L'Her.; Ait. Hort Kew. 2: 414. 1789.
Annual, tufted, villous-pubescent. somewhat viscid, erect or ascending, branched, 6'-12' high. Basal and lower leaves petioled, 3-7' long, 1/2-1' wide, pinnate, the divisions finely pinnatifid; upper leaves sessile, otherwise similar; peduncles generally longer than the leaves, umbellately 2-12-flowered; flowers purple or pink, 4"-5" broad; sepals acute. villous, about equalling the entire petals; carpels hairy; beak 1/2-1 1/2" long, its divisions spirally coiled when ripe.
Waste places and fields, Nova Scotia to Ontario, New Jersey, Pennsylvania and Michigan and very abundant from Texas to Oregon. Adventive from Europe, in our area. A common weed in the Old World. Pin-clover. Pin-grass. Pinweed. Alfilerilla. Filerie. Wild musk. April-Sept.
Erodium moschątum Willd., locally naturalized in the eastern states, has much broader less cut leaf-segments, unappendaged sepals and 2-toothed filaments.