More Caryophyllaceae - Campion Family

Cerastium glomeratum (Sticky Mouse-ear, Broad-leaved Mouse-ear Chickweed)

Bladder Campion, Silene vulgaris

Above: Cerastium glomeratum.

Cerastium glomeratum occurs widely in dry places and is native to Europe, northern Africa and southern and eastern Asia, but has been introduced into many areas including America, more southerly parts of Africa and New Zealand.

This species is a root annual and can be recognized by its small white flowers (about 5 to 6 mm in diameter) with 5 petals, divided into two at the apex, which are about the same length or slightly longer than the sepals. The pointed lanceolate (lance-head-shaped) sepals also have long articulated hairs on the central portion, especially towards the apex (and shorter glandular hairs may also be present on the sepals). The 5 sepals have narrow membranous margins. Also diagnostic of this species are the clustered flowers which remain clustered in fruit (due to the short pedicels and the corymb branches not lengthening until the fruit are nearly ripe). The fruit is a capsule, at least twice as long as the sepals, which curves upwards and opens at the apex by 10 teeth. The flower has 5 styles (in Cerastium sp. the number of capsule teeth is twice the number of styles).

The plant is pale yellow-green and covered with hairs (mainly long white hairs but also some shorter gland-tipped hairs which produce a sticky secretion). All of these diagnostic features can be seen in the photograph above.

A small apetalous form is known to occur in the British Isles, which Syme (1873, English Botany, vol. 2, George Bell & Sons) suggested that this may be a starved form (an ecotype or ecad rather than a variety).

The stems branch at their bases and are erect or ascending. The basal leaves are oblanceolate (lance-shaped with the narrow end at the base) or obovate (egg-shaped with the narrow wen at the base).

Common Chickweed (Stellaria media, Common Stitchwort, Common Starwort)

Common Chickweed

Common Chickweed is an annual (a root annual, meaning that the whole plant dies at the end of the season). the stems are decumbent (prostrate, lying horizontal) or ascending (becoming more upright towards the apex) and branched. The five small petals (1 to 3 mm long) are no longer than the five sepals and are deeply divided into two (so that it may appear as if there are ten petals arranged in 5 pairs). The petals are sometimes absent (aborted): a trait originally assigned to var. boraeana, found growing on sandy ground in parts of the British isles, but possibly a response to stress (and thus possibly an ecotype or ecad rather than a variety).

Common Chickweed

The number of stamens is variable, but often 10 or less (there are usually 5 stamens in the most common variety). When fruiting the pedicel curves (deflexes) below the fruit so that the fruit droops slightly but is said to become ascending when the fruit is ripe. The capsule is ovoid or conical and opens by 6 valves that open to about mid-way along the fruit's length. The seeds are about 1 mm in diameter, kidney-shaped and covered by tubercles. Numerous flowers are borne in terminal dichotomous cymes. There are 3 styles.

Common Chickweed

There is usually a distinctive narrow strip of articulated hairs on one side of the stem (of uncertain function). Pedicels (flower stalks) are also hairy on one side or more-or-less hairless (var. umbrosa, which also has lanceolate sepals and seeds with tubercles with star-shaped bases). The sepals have narrow scarious margins and the central region bears articulated hairs and some glandular hairs. The lower leaves are ovate and stalked; upper leaves vary from ovate to broad and elliptical and are sessile (lack stalks).

Common Chickweed

This species has a global distribution and occurs on cultivated ground (seen here on a field margin) waste places and hedgebanks and varies from 3 inches (about 8 cm) to 3 feet (1 m) in height. It can self-pollinate but is sometimes cross-pollinated by flies (http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=200007072).

Common Chickweed

Syme (1873, English Botany, vol. 2, George Bell & Sons) reports that when boiled it can be eaten like spinach, producing 7 to 8 crops a year. Syme also reports that the plant exhibits nictynasty: leaf pairs close at night, protecting the buds and the terminal pair have longer petioles so they can enclose the end of the shoot.

Stellaria holostea (Greater Stitchwort)

Greater Stitchwort

Greater Stitchwort (Stellaria holostea) was so-called as it was used (along with acorns) to treat abdominal stitches and related pains. The Latin name 'holostea' refers to the belief that it could help heal bones, due to the fact that it's stems have notable fragility: snapping easily at the nodes. Lesser Stitchwort (Stellaria graminea) is similar but the petals are more deeply divided, in Greater Stitchwort they are divided to about mid-way or less. The petals are longer than the sepals.The flowers are up to 2 cm in diameter.

Greater Stitchwort

Greater Stitchwort is a rootstock perennial, growing back from the rootstock each year for several years. The rootstock produces both shorter vegetative shoots (which are decumbent or ascending and guadrangular in cross-section) and flowering shoots.

The grass-like leaves are up to 10 cm in length and bear short stiff hairs on their margins and midribs. Softer hairs occur on the angles of the stem.

The flowering stems are elliptical in cross-section and erect (may be decumbent at the base) but ares aid to be weak, tending to rely on neighboring plants for support. The grass-like leaves lack stalks and are linear to lanceolate (lance-head shaped) with very pointed tips. The inflorescence is a dichotomous cyme with leaf-like bracts. (In a cyme each axis terminates in a flower and the flower on the central axis opens first, followed by the laterals; dichotomous means that each axis forks into two two daughter branches).

The Greater Stitchwort is largely hairless (glabrous). A few flowers are produced on long pedicels. The fruit capsule is globular and may pop open explosively. The kidney-shaped seeds are tuberculate (covered in tubercles). The seeds of may Caryophyllaceae bear tubercles, each tubercle consisting of a raised boss on a single epidermal cell and the epidermal cells interlock via interdigitating feet (Bozchaloyi, S.E. & Keshavarz, M. 2014) an architecture that gives the seed coat mechanical strength.

The tendency of the stems to lean on other plants for support, means that when those plants die away at the end of the season, the stems fall to the soil surface where they may root by developing adventitious roots (see references in Wodkiewicz, M. & Gruszcynska, B. 2014). This vegetative propagation can give rise to the development of asexual clones.

Stellaria holostea is found in woods (particularly old forests) particularly where there is not too much shade and also in grassy places, disturbed habitats, in thickets, on hedge-banks and on rocks in mountains. It is Eurasian in distribution, but is cultivated from North America and sometimes escapes to the wild there.


Caryophyllaceae - page 1


References

Stellaria seed coat: Bozchaloyi, S.E. & Keshavarz, M. 2014. Micro- and macromorphological study of Stellaria (Caryophyllaceae) and its closest relatives in Iran. Phytologia Balcanica 20 (2): 179 - 197, Sofia.

Stellaria anatomy: Keshavarzi, M. & Bozchaloyi, S.E. 2014. Leaf and stem comparative anatomical analysis of three genera of Alsinoideae (Caryophyllaceae). Iran. J. Bot. 20(1): 71 - 79. DOI: http://dx.doi.org/10.22092/ijb.2014.6158
 
Stellaria holostea ecology: Wodkiewicz, M. & Gruszcynska, B. 2014. Genetic diversity and spatial genetic structure of Stellaria holostea populations from urban forest islands. Acta Biologica Cracoviensia series botanica 56(1): 42-53. DOI: 10.2478/abcsb-2014-0004.

Plant descriptions: Syme, J. T. B. (ed) 1873. English Botany, vol. 2. George Bell & Sons.


Article page created: 17 April 2021