Species: Arabis arenicola (Richards. ex Hook.) Gelert

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Arabis arenicola (Richards. ex Hook.) Gelert

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TAXONOMY

Family:

Brassicaceae

Genus:

Arabis

Species Synonyms:

none

Common Names:

sand rockcress
arctic rock-cress

DISTRIBUTION

Canada:

Mackenzie District (Northwest Territories) - Keewatin District, Nunavut to Baffin Island, south to northwestern Saskatchewan, northern Manitoba - northern Ontario

Saskatchewan:

northwestern Saskatchewan; Lake Athabasca

Ecoregion:

Athabasca Plain, Tazin Lake Upland

HABITAT

Saskatchewan:

sand dunes and gravel flats

RARITY STATUS

Provincial Status According
to Harms (2003):

Endangered

Nature Conservancy Status:

G5 S2

Saskatchewan Species at
Risk Status:

None

COSEWIC Status:

None

Why rare?

SPECIES DESCRIPTION

Height:

10 – 30 cm

Roots:

taproot long, slender

Stems:

perennial, erect, with coarse, stiff hairs below, otherwise hairless

Leaves:

basal and on the stem; basal leaves many, tufted, 1 – 7 cm long, 4 – 7 mm wide, spoon-shaped to inversely lance-shaped, purple in age, hairless or with coarse hairs below, margin entire to shallowly toothed with up to three pairs of teeth, slightly fleshy; stem leaves few, alternate, sessile, oblong, wedge-shaped at base, margin less toothed than basal leaves

Inflorescence:

terminal, unbranched; flowers stalked

Flowers:

small; sepals < 3 mm long; petals to 5 mm long, white or pinkish

Fruits:

pod 1 – 3 cm long, 1 – 2 mm wide, ascending to spreading, hairless; seeds < 1 mm broad, in two rows, wingless; membranous partition persistent after seed dispersal

ARABIS KEY IN SASKATCHEWAN

1 Stalks and fruits strongly deflexed at maturity	2
1 Stalks and fruits erect, ascending or spreading at maturity	4

2 Basal leaves densely hairy with coarse, branching hairs; stalks gently curved downwards, pods hanging or drooping	A. holboellii var. pinetorum
2 Basal leaves with fine hairs; stalks bent abruptly near base, straight or at least not uniformly curved, pods reflexed but not hanging or drooping	3

3 Lower stem with stiff, long, spreading simple and forked hairs; basal leaves < 5 cm long, stem leaves < 2.5 cm long and 5 mm broad; pods to 6 cm long, 1.5 mm broad	A. holboellii var. collinsii
3 Lower stem finely hairy with gray or white, star-shaped hairs; basal leaves to 8 cm long, stem leaves to 4 cm long and 9 mm broad; pods to 8 cm long and 2.5 mm broad	A. holboellii var. retrofracta

4 Stalks erect or nearly so, closely appressed to stem	5
4 Stalks spreading or ascending, but not erect and appressed to the stem	7

5 Fruits round in cross section or nearly so	A. glabra
5 Fruits flat	6

6 Stem hairy below; pod 3 – 5 cm long, 0.7 – 1.0 mm wide; seeds in one row in each locule	A. hirsuta var. pycnocarpa
6 Stem commonly hairless; pod 5 – 9 cm long, 1.5 – 2.3 mm wide; seeds in two rows in each locule	A. drummondii

7 Stem leaves with ear-like lobes at the base	A. divaricarpa
7 Stem leaves without ear-like lobes at the base	8

8 Basal leaves pinnately lobed with the terminal lobe large and rounded; petals to 8 mm long; pods to 4.5 cm, < 1.5 mm broad; seeds in one row	A. lyrata
8 Basal leaves entire to toothed; petals to 5 mm long; pods to 3 cm long, about 2 mm broad; seeds in two rows	A. arenicola