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large-leaf balsamroot

Stems

up to 35 cm, tomentose; from single taproot.

Leaves

lanceolate-oblong, 1-pinnately divided;

pinnae toothed, with teeth only on lower margins;

surfaces tomentose;

basal leaves in 1–few rosettes;

blades 12–22 × 6–8 cm;

pinnae 10–36 mm wide;

petioles 7–20 cm;

cauline blades 1.5–5 × 0.3–0.9 cm;

petioles 6–9 cm.

Inflorescences

with 1 terminal head.

Involucres

14–18 × 25–30 mm.

Ray florets

14–16, yellow;

rays 35–40 × 8–11 mm.

Disc florets

~9 mm.

Phyllaries

ovate-lanceolate, 20–25 × 5–6 mm;

tips acuminate, tomentose.

Fruits

8–9 mm, glabrous.

Paleae

10–12 mm.

2n

=100 ± 2.

Balsamorhiza macrophylla

Distribution
[WildflowerSearch map]
[BONAP county map]
Discussion

Dry, open areas. Flowering May–Jul. 700–1400 m. BW. ID; east to WY. Native.

True B. macrophylla is a decaploid centered on the Wasatch Mountains in Utah and Idaho. The plants in Oregon and western Idaho are also high polyploids, but they differ morphologically from classic B. macrophylla in their denser pubescence and the shape of their leaves. These eastern plants have been given the name B. macrophylla var. idahoensis. However, further study will likely show that they have a different parentage than B. macrophylla s.s. The specific epithet “macrophylla” means large-leaved, as the leaves are much larger than those of the other members of section Balsamorhiza.

Source Flora of Oregon, volume 2, page 200
Abigail (Abby) Moore
Sibling taxa
B. careyana, B. deltoidea, B. deltoidea x Balsamorhiza sericea, B. hispidula, B. hookeri, B. incana, B. lanata, B. rosea, B. sagittata, B. sericea, B. serrata
Synonyms Balsamorhiza hookeri var. idahoensis
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