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Olympics rockcress

Georgia rockcress

Habit Perennials; (caudex branched, covered with persistent petiolar remains); moderately pubescent, trichomes simple or short-stalked, forked, (to 0.6 mm). Biennials; sparsely to moderately hirsute (at least basally), trichomes simple, mixed with fewer, short-stalked, forked ones, subsessile cruciform or 3-rayed stellate trichomes commonly on abaxial blade surfaces, sometimes plants glabrous distally.
Stems

simple or few from base (caudex), erect, unbranched, 0.7–1.1 dm, (pubescent throughout, trichomes short-stalked, forked).

simple or few from base (rosette), erect, unbranched or branched (few) distally, 3–7 dm, (hirsute basally, glabrous distally).

Basal leaves

petiole 0.3–0.6 cm, (sparsely ciliate);

blades oblanceolate to obovate, 0.4–1cm × 2–7 mm, margins entire or repand, (ciliate), apex obtuse, surfaces sparsely pubescent, trichomes simple and forked.

petiole 0.5–2 cm, (ciliate or not);

blade spatulate, oblanceolate, or obovate, 1.5–6 cm × 5–15 mm, margins dentate, apex obtuse or acute, abaxial surface moderately to sparsely pubescent, trichomes subsessile stellate, adaxial surface subglabrate or sparsely stellate.

Cauline leaves

4–6;

blade oblong, 0.6–0.8 cm × 2–3 mm, base not auriculate, margins entire, (ciliate), apex obtuse.

7–26;

blade oblong, lanceolate, or linear-lanceolate, 1.5–7 cm × 3–18 mm, base auriculate to subamplexicaul, margins dentate or entire, apex acute or obtuse, pubescent as basal leaves except distalmost leaves often glabrous.

Racemes

simple, (dense).

often simple.

Flowers

sepals (greenish), ovate, 1.5 × 0.5 mm, lateral pair not saccate basally, (glabrous);

petals white, oblanceolate, 3.5–4 × 1 mm, apex rounded.

sepals oblong, 2.5–4.5 × 1–1.5 mm, lateral pair subsaccate basally;

petals white, narrowly spatulate or oblanceolate, 6–9 × 1–1.5 mm, apex obtuse;

filaments 3–4.5 mm;

anthers oblong, 0.8–1 mm.

Fruiting pedicels

erect, (subappressed to rachis), 5–6.5 mm, (glabrous).

erect to erect-ascending, 7–16 mm, (glabrous).

Fruits

erect, (appressed to rachis), slightly torulose, 2–2.3 cm × 1 mm;

valves each with distinct midvein extending full length;

ovules 28–34 per ovary;

style 0.2–0.3 mm, (stout).

erect to erect-ascending, (often subappressed to rachis), smooth, 4–7 cm × 0.7–0.8 mm;

valves each with midvein extending full length or to middle;

ovules 38–44 per ovary;

style 0.7–1.8 mm.

Seeds

winged distally, oblong, ca. 1 × 0.5 mm;

wing ca. 0.1 mm wide.

narrowly winged throughout, oblong, 0.9–1.9 × 0.5–0.7 mm;

wing to 0.1 mm wide distally.

Arabis olympica

Arabis georgiana

Phenology Flowering Aug. Flowering Mar–Apr.
Habitat Talus slopes near glacier Stream banks, roadsides
Elevation ca. 1400 m (ca. 4600 ft) 0-200 m (0-700 ft)
Distribution
from FNA
WA
[BONAP county map]
from FNA
AL; GA
[BONAP county map]
Discussion

Arabis olympica, which is known from two collections, J. B. Flett s.n. (holotype, US; isotype, WS) and N. Buckingham 1577 (WS) that were made from Jefferson and Clallam counties, respectively, was reduced by R. C. Rollins (1936, 1941, 1993) to a variety of A. furcata. An examination of the type collections of both species reveals that they are distinct. Although the fruits and seeds of A. olympica are not fully mature, they are clearly different in width and orientation from those of A. furcata at the same developmental stage. The striking differences in fruit width and orientation, stem indument, and seed and flower size support their maintenance as distinct species. Although both species grow in Washington, the range of A. olympica seems to be restricted to Clallam and Jefferson counties and is disjunct from Chelan, Kittitas, and Yakima counties, where A. furcata grows.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Of conservation concern.

Arabis georgiana is most closely related to A. pycnocarpa, from which it is easily distinguished by having narrower fruits, longer petals, and subsessile cruciform or 3-rayed trichomes on abaxial surfaces of basal leaves. It is known only in Alabama from Bibb and Elmore counties and in Georgia from Stewart County.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 7, p. 263. FNA vol. 7, p. 261.
Parent taxa Brassicaceae > tribe Arabideae > Arabis Brassicaceae > tribe Arabideae > Arabis
Sibling taxa
A. aculeolata, A. alpina, A. blepharophylla, A. caucasica, A. crucisetosa, A. eschscholtziana, A. furcata, A. georgiana, A. mcdonaldiana, A. modesta, A. nuttallii, A. oregana, A. patens, A. pycnocarpa
A. aculeolata, A. alpina, A. blepharophylla, A. caucasica, A. crucisetosa, A. eschscholtziana, A. furcata, A. mcdonaldiana, A. modesta, A. nuttallii, A. olympica, A. oregana, A. patens, A. pycnocarpa
Synonyms A. furcata var. olympica
Name authority Piper: Contr. U.S. Natl. Herb. 16: 208. (1913) R. M. Harper: Torreya 3: 88. (1903)
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