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cotton weed plant

COTTONWEED

Achillea maritima
Daisy & Dandelion Family [Asteraceae]

18th Sept 2011, Lady’s Island Lake, Wexford, Ireland. Photo: © Paula O’Meara
A rare low plant, to a foot high, growing near the sea amidst Sea Spurge.

18th Sept 2011, Lady’s Island Lake, Wexford, Ireland. Photo: © Paula O’Meara
Is so covered in a tight matt of white hairs that it looks frosted.

18th Sept 2011, Lady’s Island Lake, Wexford, Ireland. Photo: © Paula O’Meara
At the top grow several tightly-packed flower heads of deep yellow flowers.

18th Sept 2011, Lady’s Island Lake, Wexford, Ireland. Photo: © Paula O’Meara
The leaves are short and so tightly packed around the stem as to completely hide it from view.

18th Sept 2011, Lady’s Island Lake, Wexford, Ireland. Photo: © Paula O’Meara
The Daisy-type flowers lack ray-florets altogether, and consist only of several heads of disc florets with their usual five short triangular petals.

18th Sept 2011, Lady’s Island Lake, Wexford, Ireland. Photo: © Paula O’Meara
Short white hairs so densely cover the plant that hardly any green is visible, just the briefest tint.

18th Sept 2011, Lady’s Island Lake, Wexford, Ireland. Photo: © Paula O’Meara
The disc-florets all huddle together. Note that the disc florets have but 4 ‘petals’ (rather than the more usual 5). There are no ray florets.

18th Sept 2011, Lady’s Island Lake, Wexford, Ireland. Photo: © Paula O’Meara
Flowers going to seed.

18th Sept 2011, Lady’s Island Lake, Wexford, Ireland. Photo: © Paula O’Meara
Leaves short, less than an inch long, linear and with an abrupt 90° chamfer at the end.

18th Sept 2011, Lady’s Island Lake, Wexford, Ireland. Photo: © Paula O’Meara
Some leaves have short teeth, a little like nodules along the edge.

Easily confused semantically with : Buttonweed [a plant of similar name belonging to the same Daisy & Dandelion Family but which looks more like a Colt’s-foot plant but one curiously lacking ray-florets]. Nor should it be confused with Cotton Thistle, a thistle covered in longer white hairs.

Some similarities to : Lavender-cotton , another member of the Daisy & Dandelion Family, but that is a low shrub, which also has deep yellow and ray-less flowers, is covered in a dense short matt of white hairs, and where the short pinnately-lobed leaves sparsely populate the stems allowing them to be seen.

Slight resemblance to : the Cudweed s such as Jersey Cudweed which are also covered in a dense matt of white hairs. They too belong to the same Daisy & Dandelion Family.

No relation to: Black Cottonwood , a type of Poplar tree.

Not to be semantically confused with : Buttonweed (Cotula coronopifolia) [which has a similar sounding name and belongs to the same Dandelion & Daisy Family (Asteraceae)]

Uniquely identifiable characteristics

Rare! A salt-tolerant plant previously found in up to 20 scattered locations near the sea in the South of England and Ireland, but since the start of the new Century now found in only one location: in County Wexford, Ireland, by the sea.

CONSTITUENTS

MONOTERPENOIDS

The cis- version of Chrysanthenyl Acetate, a monoterpenoid, is found in Cottonweed

Chrysanthenone , which is very similar, is also found. An isomer of Chrysanthenone is Verbenone, but this has not reportedly been found in the plant, but is found in similar plants.

Verbenone has a pleasant aroma and acts as an insect repellent in some trees and plants. It is used in aromatherapy and in perfumes, spices, herbal teas and, in the L-isomeric form, as a cough suppressant and expectorant under the medical name of Levoverbenone.

Filifolone is also found in Cottonweed. Note that Chrysanthenone has a 4-membered ring conjoined to a 6-membered ring, whereas Filifolone is almost identical but with the 4-membered ring conjoined onto a 5-membered ring. It therefore has one CH2 less than does Chrysanthenone.

LIGNINS and LIGNOLS

PinoResinol is the dimer of Coniferyl Alcohol, although the 5-membered ring of PinoResinol has been broken. PinoResinol is a lignan found in a few other plants too such as Olive (Olea europaea) (and in Olive Oil), in some Forsythia and Pieris species, in Sesame seeds, in Brassica vegetables and frequently in woody resinous plants such as Styrax trees. It has two fused Furan rings in the centre which are formed by the closure of the HydroxyPropenol moiety in Coniferyl Alcohol as part of the dimerisation process. PinoResinol is found in the Cabbage White butterfly (probably from the cabbages it consumes) where it acts as a defence chemical against ant attack.

COTTONWEED Achillea maritima Daisy & Dandelion Family [Asteraceae] 18th Sept 2011, Lady’s Island Lake, Wexford, Ireland. Photo: © Paula O’Meara A rare low

balloon cotton bush

A small shrubby plant usually growing up to 2 m tall. Its stems and elongated leaves (3.5-12 cm long and 5-16 mm wide) exude a milky sap when damaged. Its clusters of white or pinkish flowers have a crown-like structure at its centre. Its distinctive balloon-like fruit (5-7.5 cm long) are covered with soft spines (7-10 mm long). These fruit contain many black seeds topped with silky tufts of white hairs.

A widely naturalised species that is most common in the eastern parts of the country. It is very common in the coastal and sub-coastal districts of central and southern Queensland and in the north-eastern corner of New South Wales. Less common or occasional in northern Queensland, in other parts of New South Wales, in south-eastern South Australia, and near Perth in south-western Western Australia. Also naturalised on Norfolk Island and Lord Howe Island. Naturalised overseas in Mauritius, India, Sri Lanka, Hong Kong, Hawaii, New Caledonia, the Caribbean and beyond its native range in Africa.

balloon cotton bush A small shrubby plant usually growing up to 2 m tall. Its stems and elongated leaves (3.5-12 cm long and 5-16 mm wide) exude a milky sap when damaged. Its clusters of white or