Flora of North America species comparison

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Alyssum obovatum

American madwort
Habit Perennials; (cespitose, caudex often woody); canescent throughout, trichomes 10–25-rayed.
Stems

often several from base (often with sterile shoots), usually erect or ascending, 0.7–1.5(–2) dm.
Cauline leaves

subsessile;

blade broadly oblanceolate, obovate-spatulate, or obovate, 0.6–1.4(–1.7) cm × (1–)2–6 mm (gradually smaller distally), base attenuate, apex rounded, obtuse, or subacute. (Racemes corymbose, simple, or in panicles terminating each stem.) Fruiting pedicels divaricate, straight, slender, (2–)3–7(–9) mm, trichomes uniformly stellate.
Flowers

sepals oblong, 1.5–2 × 0.7–1 mm, stellate-pubescent;

petals yellow, broadly spatulate, 2.5–3.5(–4) × 1–1.5 mm, base attenuate, apex often obtuse or rounded, glabrous abaxially;

filaments: median pairs unilaterally broadly winged, apically 1-toothed, lateral pair with lanceolate or narrowly oblong basal appendage, apically obtuse or subacute, 1.5–2 mm;

anthers oblong, 0.3–0.4 mm.
Fruits

broadly elliptic or obovate, 3–4.5(–5) × 2.5–3.5 mm, apex obtuse to rounded;

valves inflated at middle or on 1 side, flattened at margins, densely stellate-pubescent;

ovules (1 or) 2 per ovary;

style (slender), 1.5–2 mm, glabrous.
Seeds

ovoid, compressed, 1–1.7 × 0.8–1.2 mm, not winged or margined.
2n

= 16, 32.

Alyssum obovatum
Phenology Flowering May–Jul.
Habitat Mountain slopes, cliffs, gravel, rocky places
Elevation 500-1500 m (1600-4900 ft)
Distribution
from FNA
AK; YT; c Asia; e Asia
[BONAP county map]
Source FNA vol. 7, p. 250.
Parent taxa Brassicaceae > tribe Alysseae > Alyssum
Sibling taxa
A. alyssoides, A. desertorum, A. murale, A. simplex, A. szowitsianum
Synonyms Odontarrhena obovata, A. americanum, A. biovulatum, A. fallax
Name authority (C. A. Meyer) Turczaninow: Bull. Soc. Imp. Naturalistes Moscou 10: 57. (1837)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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