Cerastium diffusum

Carnation & Campion (Pink) Family [Caryophyllaceae]

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22nd May 2017, Loggerheads Country Pk, North Wales. Photo: © RWD
A low-growing (up to 8cm - occasionally 30cm) decumbent to erect annual which usually grows near the sea, but these specimens were high up a hill well inland in North Wales. (Ignore the whorls of pointed-tipped leaves - those belong to a Bedstraw)

22nd May 2017, Loggerheads Country Pk, North Wales. Photo: © RWD
Unusually for Mouse-ears which usually have 5 petals, Sea-mouse Ear usually has but 4 petals, 4 sepals, and 4 styles. The petals are deeply cleft. The petals are said to be 3/4 ths the length of the sepals, but all photos your Author has found on the internet have the petals about stretching to about the same radius as the sepals (perhaps we are supposed to measure their lengths independently, rather than comparatively in-situ?). If the flowers have 5 petals, then they will also (usually) have 5 sepals and 5 styles. The numbers of stamens they have varies from 4 to 5, but, it seems, not necessarily mirroring the number of petals. For instance, this specimen has 4 petals but 5 stamens, whilst the ones in the set above this one have 4 of each (one has obviously dropped off on the 1st).

22nd May 2017, Loggerheads Country Pk, North Wales. Photo: © RWD
This specimen has narrow white margins on the sepals whilst others seem not to.

22nd May 2017, Loggerheads Country Pk, North Wales. Photo: © RWD
The sepals have both glandular sticky hairs and normal hairs. The green parts of the sepals are uniformly green. They also have no white margins. Cream-coloured anthers and a stigma splitting near the end into 4 white styles.

Not to be semantically confused with : Mouse-ear-hawkweed (Pilosella officinarum), Mousetail Plant (Arisarum proboscideum), Mousetail (Myosurus minimus) or Starwort Mouse-ear (Cerastium cerastoides) [plants with similar names belonging to differing families].

Easily mis-identified as : other Mouse-ears and to a lesser extent Stitchworts (which all have white flowers with cleft petals, but in the case of Stitchworts the clefts are very deep). However, all those nominally have flowers with five petals whereas Sea Mouse-ear usually has only four petals (only occasionally 5). Uniquely identifiable characteristics

Distinguishing Feature : A Mouse-ear with only 4 white (cleft) petals.

It is a native annual plant which occurs most often by or near the sea on sand, shingle, or open shortish grassland. It is occasionally found further inland, as in these photos, or alongside salted roads and used to be found in amongst railway ballast. As is to be expected growing near the sea it is a Halophyte, tolerating a salty diet. But it doesn't grow in the tidal zone where it would get washed away twice a day... The leaves are 5-18mm long and often with a purple rim like the tips of the sepals, which are supposed to be fringed white (they are in some of the photos from Loggerheads Country Park, but not in others). According to the books the hairs on the sepals never extend beyond the tips of the sepals, but it is well known that plants cannot read and often blatantly break the rules, as do the specimens from the Loggerheads Country Park above. The flowers are small, only 3-6mm across.

The bracts are uniformly green. The plant is only rarely hairless, preferring to have many glandular hairs and some non-glandular hairs over the plant (except, of course, the petals and sex organs).

The fruit capsule is 5 to 7.5mm long, straight and usually has 8 teeth (up to 10).

  Cerastium diffusum  ⇐ Global Aspect ⇒ Caryophyllaceae  

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Cerastium diffusum

Carnation & Campion (Pink) Family [Caryophyllaceae]