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Georgia rockcress

Waldo rock-cress

Habit 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. Perennials; (caudex simple or branched, covered with persistent petiolar remains); sparsely to moderately pubescent, trichomes sub-setiform, bulbous-based, simple, (to 1.5 mm), often mixed with fewer, forked, stalked ones.
Stems

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

simple or few from base (caudex), erect, unbranched, (0.6–)1.5–3.5(–4.5) dm, (sparsely to densely hirsute basally or throughout).

Basal leaves

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.

petiole 0.3–1.5 cm, (ciliate);

blade oblanceolate to obovate, (0.5–)1–3(–4) cm × (2–)3–6(–10) mm, margins entire, repand, or obtusely dentate, (ciliate), apex obtuse, surfaces pubescent, trichomes usually simple, sometimes mixed with fewer forked ones, rarely subglabrate.

Cauline leaves

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.

3–6 (or 7);

blade oblong, 0.4–1(–1.5) cm × (1–)2–4 mm, base not auriculate, margins entire or repand, apex obtuse.

Racemes

often simple.

simple, (dense).

Flowers

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.

sepals (purple), oblong, 4–8 × 1.5–2.5 mm, lateral pair saccate basally;

petals purple, spatulate, (9–)10–18(–20) × (2.5–)3.5–6(–8) mm, apex obtuse;

filaments 4–9 mm;

anthers oblong, 1.5–2 mm.

Fruiting pedicels

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

ascending to suberect, 8–12(–15) mm, (subglabrate or sparsely pubescent).

Fruits

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.

ascending to suberect, not torulose, sometimes slightly curved, 3.5–6.5 cm × 1.5–2 mm;

valves each with prominent midvein extending full length;

ovules 24–36 per ovary;

style (0.7–)1–2 mm.

Seeds

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

wing to 0.1 mm wide distally.

narrowly winged nearly throughout except wider distally, oblong, 1.5–2.3 × 1–1.3 mm;

wing 0.1–0.3 mm wide.

2n

= 32.

Arabis georgiana

Arabis aculeolata

Phenology Flowering Mar–Apr. Flowering Mar–May(-Jun).
Habitat Stream banks, roadsides Serpentine slopes, rocky hillsides
Elevation 0-200 m (0-700 ft) 200-1800 m (700-5900 ft)
Distribution
from FNA
AL; GA
[BONAP county map]
from FNA
OR
[WildflowerSearch map]
[BONAP county map]
Discussion

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.)

Arabis aculeolata is known only from Curry, Douglas, and Josephine counties.

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

Source FNA vol. 7, p. 261. FNA vol. 7, p. 265.
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. mcdonaldiana, A. modesta, A. nuttallii, A. olympica, A. oregana, A. patens, A. pycnocarpa
A. alpina, A. blepharophylla, A. caucasica, A. crucisetosa, A. eschscholtziana, A. furcata, A. georgiana, A. mcdonaldiana, A. modesta, A. nuttallii, A. olympica, A. oregana, A. patens, A. pycnocarpa
Name authority R. M. Harper: Torreya 3: 88. (1903) Greene: Leafl. Bot. Observ. Crit. 2: 69. (1910)
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