SEA SANDWORT

Honckenya peploides

Carnation & Campion (Pink) Family [Caryophyllaceae]

month8may month8jun month8june month8jul month8july

status
statusZnative
flower
flower8white
inner
inner8green
inner
inner8cream
morph
morph8actino
petals
petalsZ5
stem
stem8round
stem
stem8hollow
sex
sexZdioecious

3rd June 2010, Walney Island, Cumbria. Photo: © RWD
A prostrate perennial plant that grows on sand and shingle exclusively on the upper-beach parts of coastal shores.


3rd June 2010, Walney Island, Cumbria. Photo: © RWD
It is sub-dioecious, having characteristics of both dioecism and hermaphroditism, a chimera between having male and female flowers on separate plants and having flowers with both male and female characteristics. When separate (dioecious) the male flower petals are much larger than those of female flowers (which seem to be quite rare) (E&OE).


28th May 2012, Rhos Point, Colwyn Bay, North Wales. Photo: © RWD
An un-opened flower bud surrounded by five green sepals.


3rd June 2010, Walney Island, Cumbria. Photo: © RWD
Usually with five white petals, this specimen has but four petals and only four sepals and eight (rather than 10) filaments too.


3rd June 2010, Walney Island, Cumbria. Photo: © RWD
 The male flowers have white petals that are just a little shorter than the sepals behind. (It is said that female flowers have much shorter petals). Male flowers have ten stamens (with cream coloured pollen), as here.


28th May 2012, Rhos Point, Colwyn Bay, North Wales. Photo: © RWD
This specimen has an outer ring of five stamens with pollen on the anthers, and an inner ring of five still enclosed within their double-lobed pollen sacs. Maybe this is one of those flowers which are displaying it's characteristic mixed genetics sub-dioecious nature. The green fruit is developing in the centre and has three stigmas.


8th June 2016, brick shoreline, Hightown, Sefton Coast. Photo: © RWD
  This specimen is displaying a developing fruit with three white styles still atop and 10 anthers, most with cream-coloured pollen - so this flower is hermaphroditic.


8th June 2016, brick shoreline, Hightown, Sefton Coast. Photo: © RWD
  The filaments often emerge through an orange-coloured 'washer' surrounding the ovary.


8th June 2016, brick shoreline, Hightown, Sefton Coast. Photo: © RWD
The cream coloured pollen and white pollen sacs.


11th June 2009, Hall Road, Sefton Coast, Lancs. Photo: © RWD
Could these be female flowers with three stigmas protruding (it can be up to five).


3rd June 2010, Walney Island, Cumbria. Photo: © RWD
The green fruits enlarge.


3rd June 2010, Walney Island, Cumbria. Photo: © RWD
Fruits almost spherical and green; they have three valves (the fruit splits into three to release the seeds).


3rd June 2010, Walney Island, Cumbria. Photo: © RWD
Nearly ripe fruits with remnants of stigma atop.


27th July 2007, Hall Road, Sefton Coast, Lancs. Photo: © RWD
Ripe marrowfat-pea sized fruits are yellowish-green. They have several reddish brown seeds within.


7th Aug 2009, Hall Road, Sefton Coast, Lancs. Photo: © RWD
Leaves are curving triangular, stalk-less and stack up in neat tapering rows. It is likely that these shoots have arisen from plants that were extensively buried by sand, they have morphologically distinct shapes, see text below.


7th Aug 2009, Hall Road, Sefton Coast, Lancs. Photo: © RWD
The plants are very architectural with four sides of leaves.


7th Aug 2009, Hall Road, Sefton Coast, Lancs. Photo: © RWD
A single branch can grow to 25cm in length, if not in height. Leaves look succulent, as do the hollow stems.


27th July 2007, Hall Road, Sefton Coast, Lancs. Photo: © RWD
Stems usually bifurcating into branches of equal length.


3rd June 2010, Walney Island, Cumbria. Photo: © RWD
The leaves are dotted in salt-like pores? (possibly a means by which to expel un-wanted but absorbed salt? ). Like Prickly Saltwort there are translucent polyps around the leaf-edges, perhaps an adaptation to highly saline conditions.


8th June 2016, brick shoreline, Hightown, Sefton Coast. Photo: © RWD
The leaf-edges look like thin moulding flashes with tiny transparent teeth.


Uniquely identifiable characteristics

Distinguishing Feature :

It is sub-dioecious, sometimes having male and female flowers on differing plants, and sometimes flowers with both male and female characteristics. The petals are shorter on female flowers. Basically, it is all mixed up.

It is a perennial. Over winter the plant has no presence on the surface, apart from short stumps of dead hollow stems, it is dormant underground awaiting spring. If, however, it becomes extensively buried by sand (perhaps through the action of a storm or tidal wave) then it starts to clone itself at intensively forming. Following burial, morphologically different shoots eventually break surface with smaller, highly regularly set and densely positioned leaves. See photos above.

Many other sand and shingle upper-beach plants have adapted themselves to repeated burial by sand, especially Saltwort (Salsola kali).

The triangular leaves are frequently geometrically arranged in quadrature around the stem making for a very architectural plant. The only other plant growing near the sea that has similarly architectural leaves are that of Sea Milkwort (Glaux maritima) but the leaves are oval rather than triangular and it grows on salt-marshes rather than the bare sand in which Sea Sandwort grows.

Growing by the sea, Sea Sandwort is necessarily salt-tolerant, a halophyte. No plant requires such enormous salt concentrations as found in the sea, and have adapted themselves to deal with the absorbed salt. However, the Author can find no evidence that Sea Sandwort is a metallophyte or sequestrator of heavy-metals as is Thrift (Armeria maritima), a plant higher up the shore-line inhabiting the drier grassy-sward areas of salt-marshes.

A Sandwort by common name, although it is in a differing genus to the other Sandworts such as Thyme-leaved Sandwort (Arenaria serpyllifolia) and in yet another genus to another Sandwort, Three-Nerved Sandwort (Moehringhia trinervia). However, all three are in the same Carnation & Campion (Pink) Family, Caryophyllaceae.


  Honckenya peploides  ⇐ Global Aspect ⇒ Caryophyllaceae  

Distribution
 family8Carnation & Campion (Pink) family8Caryophyllaceae

 BSBI maps
genus8Honckenya
Honckenya
(Sea Sandwort)

SEA SANDWORT

Honckenya peploides

Carnation & Campion (Pink) Family [Caryophyllaceae]