Geum macrophyllum
Geum geniculatum
benoîte à grandes feuilles, bigleaf avens, large-leaf avens
bent avens
30–110 cm, puberulent and hirsute or sparsely hirsute.
50–84 cm, sparsely hirsute proximally, hirsute 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 14–30 cm, blade interruptedly lyrate-pinnate, major leaflets 1–5, mixed with 2–5 minor ones, terminal leaflet slightly to much larger than major laterals;
cauline 4–12 cm, stipules ± free, 7–20 × 4–8 mm, blade pinnate, 3-foliolate, or simple and 3-lobed.
3–16-flowered.
5–15-flowered.
densely puberulent, sometimes with scattered longer hairs, sometimes stipitate-glandular.
densely pilose, some hairs septate-glandular.
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.
nodding;
epicalyx bractlets 2.5–3 mm;
hypanthium green with purple tinge at base to greenish maroon;
sepals erect to erect-spreading, 5–8 mm;
petals erect, white, pink, or lavender, spatulate-obovate, 5–7 mm, ± equal to sepals, apex rounded, truncate, or shallowly emarginate.
sessile or on less than 1 mm stipes, puberulent.
sessile, densely bristly.
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.
geniculate-jointed, proximal segment persistent, 2–4.5 mm, apex hooked, septate-glandular hairs on basal 1/2, distal segment very tardily deciduous, 5–8 mm, pilose except apical 1–2 mm, with some glandular hairs.
Geum macrophyllum
Geum geniculatum
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 geniculatum is enigmatic and is currently known from 15 populations in western North Carolina and eastern Tennessee. As a rare plant, it has attracted far less attention than G. radiatum, which is also known from the same region. Although G. geniculatum is not listed federally as endangered or threatened, it is listed as threatened by North Carolina and as endangered by Tennessee.
W. Gajewski (1957) speculated that Geum geniculatum is a hybrid, with one of the parents being G. rivale. K. R. Robertson (1974) pointed out that the nearest locality for G. rivale is in West Virginia and that pollen stainability of G. geniculatum is very high. Geum geniculatum may be of hybrid origin; it cannot be a first-generation hybrid. North American taxonomists have treated it as a valid species.
(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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SW CO Wildflowers, Turner Photog. 
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