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 rotundifolium L. Sp. Pl. 683. 1753.
Annual, often tufted, 6'-18' high, much branched, softly pubescent with spreading white purple-tipped glandular hairs. Leaves reniform-orbicular, broader than long, 1 1/2' wide, cleft about to the middle into 5-9 obtuse broad lobes, which are 3-5-toothed; petioles slender, those of the basal leaves elongated; flowers purple, 2"-3" broad; sepals ovate, or oval, short-pointed, somewhat shorter than the entire obovate petals; ovary and capsule-lobes hairy, not wrinkled; beak pubescent, about 6" long, pointed with a short awn; seeds reticulated.
Geranium carolinianum L. Sp. Pl 682. 1753.
Annual, erect, generally branched from the base and also above, stout, 6'-15' high, loosely pubescent with spreading often glandular gray hairs. Leaves petioled, reniform-orbicular in outline, 1'-3' wide, deeply cleft into 5-9 oblong or obovate cuneate toothed or lobed segments; peduncles rather short and stout, 2-flowered; flowers in compact clusters, pale pink or whitish, 4"-6" broad; sepals ovate, ciliate, awn-pointed, about equalling the obovate emarginate petals; ovary-lobes hispid-pubescent; persistent filaments not longer than the carpels; beak nearly 1' long, short-pointed; seeds ovoid-oblong, finely reticulated.
In barren soil, Nova Scotia(?), Ontario to British Columbia, Massachusetts, Florida and Mexico. Also in Bermuda and Jamaica. April-Aug.
Similar to the preceding species, but taller, the stems usually more slender, loosely pubescent. Leaves slender-petioled, somewhat angulate in outline, the segments oblong or linear-oblong, mostly narrower; peduncles slender, 2-flowered, the inflorescence loose; sepals lanceolate, awn-pointed; ovary-lobes pubescent; persistent filaments longer than the carpels; beak about 1' long, long-pointed, its tip 2"-3" long; seeds reticulated.
Geranium dissectum L. Amoen. Acad. 4: 282. 1760.
Closely related to the two preceding species, but smaller in every way, more slender, the branches decumbent or ascending; leaves seldom more than 1 1/2' wide deeply cleft into narrower segments; inflorescence loose; peduncles short, 2-flowered; flowers purple, about 3" broad; sepals ovate, awned, equalling or slightly longer than the notched petals; capsule-lobes and beak pubescent; seeds ovoid or globose, deeply pitted.
In waste places, and in ballast in New York and New Jersey. Also in the far Northwest. Fugitive from Europe. Wood-geranium. June-Sept.