HAIRY ROCK-CRESS

Arabis hirsuta

Cabbage Family [Brassicaceae]

month8may month8jun month8june month8jul month8july month8aug

status
statusZnative
flower
flower8white
inner
inner8brown
morph
morph8actino
petals
petalsZ4
stem
stem8round
sex
sexZbisexual

15th May 2008, Warton Crag, Lancs. Photo: © RWD
Heads straight for the sky! Usually only a foot high, with hairy leaves on the lower half of the stem pointing upwards, and many longish seed pods on the upper half, both close to the stem. White flowers atop.


9th June 2018, Waitby Greenriggs, Kirby Stephen, Yorkshire Photo: © RWD
Narrow lanceolate leaves held upright and close to the stem. The stems are unbranched, one per basal rosette.


15th May 2008, Warton Crag, Lancs. Photo: © RWD
Seed pods longer than their stalks, cylindrical, and close to the stem, which is also hairy.


5th May 2011, Lathkilldale, Derbyshire. Photo: © RWD
Flower head small and compact, with many white petalled flowers at the top. Any upper leaves narrower and clasping the stem.


5th May 2011, Lathkilldale, Derbyshire. Photo: © RWD
Four white petals with rounded ends.


5th May 2011, Lathkilldale, Derbyshire. Photo: © RWD
Flowers 7 - 10mm across with nominally six stamens, although some have as few as four.


5th May 2011, Lathkilldale, Derbyshire. Photo: © RWD
Un-opened flower buds brownish-purple and shaped like 1/8th inch flat-blade screw-drivers.


9th June 2018, Waitby Greenriggs, Kirby Stephen, Yorkshire Photo: © RWD
A month later, when all the screwdriver-tipped un-opened flower buds have all opened. The flowers have 6 stamens with yellowish anthers in a slightly flattened hexagogonal arrangement. In the centre at roughly the same height as the anthers is a single green style tipped by a yellowish discoidal stigma.


10th June 2009, Smardale, Yorkshire. Photo: © RWD
Seed pods brown, cylindrical, longer than their stalks, held upright and close to the main stem.


9th June 2018, Waitby Greenriggs, Kirby Stephen, Yorkshire Photo: © RWD
The seed pods, some of which are square like those of Willowherbs, are also held erect and easily exceed the petals in height. They are 18 to 45mm long. The four sepals are nearly upright, with a pale yellow base and tapering to a green bluntish tip, some having a membaneous semi-translucent border.


9th June 2018, Waitby Greenriggs, Kirby Stephen, Yorkshire Photo: © RWD
The hairs around the stem and on the edges of leaves are somewhat randomly directed.


15th May 2008, Warton Crag, Lancs. Photo: © RWD
Stem leaves hairy both sides, lanceolate, only slightly toothed and held upright and close to the stem.


9th June 2018, Waitby Greenriggs, Kirby Stephen, Yorkshire Photo: © RWD
Lowest leaves still bolt upright but a little wider than those nearer the summit.


10th June 2009, Smardale, Yorkshire. Photo: © RWD
Basal leaves noticeably hairy and lanceolate. Notice several secondary stems about to sprout from near the centre.


Not to be consuded with : Hoary Rock-Rose (Helianthemum oelandicum) a flower from a differing family.

Some similarities to : Thale Cress and other short white-flowered members of the Cabbage Family such as Hairy Bitter-cress, Hoary Whitlowgrass and other Rock-cresses, but Hairy Rock-cress has leaves AND seed pods kept very close to the stem amongst many other slight differences.

It is native. Habitat includes grassland and rocks on lime, and sand dunes and is found scattered throughout the British Isles.


USE BY BUTTERFLIES
LAYS EGGS ON CATERPILLAR CHRYSALIS BUTTERFLY
Orange-tip



  Arabis hirsuta  ⇐ Global Aspect ⇒ Brassicaceae  

Distribution
 family8Cabbage family8Brassicaceae
 BSBI maps
genus8Arabis
Arabis
(Rock-Cresses)

HAIRY ROCK-CRESS

Arabis hirsuta

Cabbage Family [Brassicaceae]

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