Geum macrophyllum
Geum radiatum
benoîte à grandes feuilles, bigleaf avens, large-leaf avens
Appalachian avens, spreading avens
30–110 cm, puberulent and hirsute or sparsely hirsute.
10–45(–60) cm, densely hirsute proximally to puberulent distally.
basal 10–45 cm, blade interruptedly lyrate-pinnate, major leaflets 5–9, alternating with 4–15 minor ones, terminal leaflet usually much larger than major laterals;
cauline 2–12 cm, stipules ± free, 7–23 × 3–12 mm, blade lyrate-pinnate, pinnate, 3-foliolate, or simple and 3-lobed.
basal 10–30 cm, blade strongly lyrate-pinnate, sometimes simple, major leaflet 1, minor leaflets 1–6, terminal leaflet much larger than minor laterals;
cauline 1.2–4 cm, stipules not evident, blade bractlike, not resembling basal, simple.
3–16-flowered.
3–10-flowered.
densely puberulent, sometimes with scattered longer hairs, sometimes stipitate-glandular.
glandular-hairy.
erect;
epicalyx bractlets often absent, 0.5–2 mm;
hypanthium green;
sepals erect-spreading but soon reflexed, 2.5–5.5 mm;
petals spreading, yellow, obovate, broadly elliptic, or suborbiculate, 3.5–7 mm, longer than sepals, apex rounded.
erect;
epicalyx bractlets 2–5 mm;
hypanthium green;
sepals spreading in flower, erect in fruit, 6–10 mm;
petals spreading, yellow, orbiculate to obcordate, 9–16 mm, longer than sepals, apex emarginate.
sessile or on less than 1 mm stipes, puberulent.
sessile, glabrous.
geniculate-jointed, proximal segment persistent, 2.5–6 mm, apex hooked, sparsely to densely stipitate-glandular, distal segment deciduous, 1–2 mm, pilose in basal 1/3, hairs much longer than diam. of style.
wholly persistent, not geniculate-jointed, 8–12 mm, apex not hooked, pilose and stipitate-glandular in basal 1/3.
= 42.
Geum macrophyllum
Geum radiatum
Varieties 2 (2 in the flora).
Characters useful in recognizing specimens of Geum macrophyllum are yellow petals, epicalyx bractlets often absent, proximal style segment sparsely to densely stipitate-glandular, and fruiting receptacles puberulent. Across its broad North American range from Alaska to California and Nova Scotia, G. macrophyllum exhibits considerable variation. Based largely on the shape of the terminal leaflet of the basal leaves and the degree of dissection and shape of the divisions of the distal cauline leaves, P. A. Rydberg (1913b) distinguished three species within the range of variation treated here as one species. Basal leaves of G. macrophyllum in the strict sense (var. macrophyllum in this treatment) have relatively large reniform to rounded terminal leaflets and the distal cauline leaves are three-cleft into rhombic or cuneate lobes. The basal-leaf terminal leaflets of G. perincisum (= var. perincisum) are only slightly larger than the laterals and are deeply lobed into rhombic-obovate segments; the distal cauline leaves are dissected into oblanceolate divisions. Both basal and cauline leaves of G. oregonense (= var. perincisum) are intermediate between those of G. macrophyllum and G. perincisum. W. Gajewski (1955) crossed all three taxa under discussion and examined leaf morphology and cytology of the F1 and F2 hybrids. He concluded that they were distinct but not yet completely separated species. Fairly well correlated with the more dissected leaves of G. oregonense and G. perincisum is the presence of minute stalked glands on the pedicels. The treatment here follows H. M. Raup (1931) in recognizing two varieties of G. macrophyllum based more on pedicel glandularity than leaf morphology.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Of conservation concern.
Geum radiatum is closely related to G. calthifolium and G. peckii. The morphologic differences among them are slight compared to the discontinuities separating other Geum species. On the basis of morphology it would be possible to combine all three in a single species. Yet they occupy distinct ranges separated by a minimum of 1200 km. Traditionally, they have been treated as separate species, and recently I. G. Paterson and M. Snyder (1999) reported molecular genetic evidence for continuing to recognize G. peckii and G. radiatum as separate species.
Geum radiatum is listed as an endangered species by the U.S. Fish and Wildlife Service.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Pedicels not glandular-puberulent; cauline leaves with distal simple and 3-lobed (divided less than 3/4 to base), lobes rhombic-oblong. | var. macrophyllum |
1. Pedicels glandular-puberulent; cauline leaves with distal 3-foliolate or simple and 3-lobed (divided almost to base), lobes oblanceolate to obovate. | var. perincisum |
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