Mayweeds & Chamomiles
What are they?
The compound heads of small yellow florets and outer ring of white petals show these plants to be members of the daisy and dandelion family - the Asteraceae. These are annuals or low-growing perennials, mostly with deeply cut leaves and often distinctive scents.
Where are they found?
These plants are mostly native annuals of open ground and can often grow in great abundance around the margins of arable fields and along tracksides and rough ground. Some are perennials of garden origin and may occasionally appear where garden waste has been dumped.
Identification
These plants are all rather similar in the general appearance of their foliage and flowers, so identification relies on very careful scrutiny of the flowers and seeds. Thus, non-flowering plants can be very difficult to identify, though familiarity with the various scents that they emit can be useful. As with many members of the Asteraceae, features of the phyllaries can be useful - those are the greenish bracts that surround the outside of the flowerhead. It can also be useful to open up a flowerhead to see if the base is solid or hollow, while a hand lens may be required to check for tiny bracts called scales that occur amongst the florets in some species.
Scentless Mayweed Tripleurospermum inodorum
Introduced annual. Widespread in open and disturbed ground throughout the region, especially as an agricultural and garden weed. Flowers June to September. Leaves bright green with relatively long and narrow segments. Flowerheads solid inside at the base with the central disk only elongating slightly at maturity. Flowerhead scales absent. Phyllaries green with darker margins. Seeds strongly three-ribbed and with two resin glands (appearing as dark, rounded spots towards the top). As the name suggests, the foliage has no obvious scent to it.
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Sea Mayweed Tripleurospermum maritimum
Native biennial or short-lived perennial. A coastal species, found in a variety of coastal habitats. Also occasionally reported from inland sites where presumably accidentally introduced. Flowers June to September. Leaves bright green with relatively short and fleshy segments, adpated to cope with a salty environment. Flowerheads solid inside at the base with the central disk only elongating slightly at maturity. Flowerhead scales absent. Phyllaries green with darker margins. Seeds strongly three-ribbed and with two resin glands (appearing as dark, rounded spots towards the top). The foliage has no obvious scent to it.
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Hybrid Mayweed Tripleurospermum maritimum x T. inodorum
The hybrid between the introduced Scentless Mayweed and the native Sea Mayweed, most often found in disturbed, coastal habitats. Flowers June to September. Leaves bright green and appearing intermediate between the parents, with slightly fleshy leaves that have longer segments that those of Sea Mayweed. Flowerheads solid inside at the base with the central disk only elongating slightly at maturity. Flowerhead scales absent. Seeds strongly three-ribbed and with two resin glands (appearing as dark, rounded spots towards the top). The foliage has no obvious scent to it. Some authorities consider Sea and Scentless Mayweeds to be subspecies of a single species and therefore these hybrids may simply be considered intermediates.
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Scented Mayweed Matricaria chamomilla
Introduced annual. Widespread as a weed of cultivation and on other disturbed soils. Most common in Fenland and on the heavier boulder clays, less frequent on drier, sandy soils. Flowers June to August. Leaves bright green with narrow segments. Flowerheads hollow inside at the base with the central disk elongating markedly at maturity into a tall dome and the white petals reflexing downwards. Flowerhead scales absent. Phyllaries green, rather narrow and with dark tips. Seeds with four to five ribs and without resin glands. Foliage sweetly scented.
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Stinking Chamomile Anthemis cotula
Introduced annual. Once a widespread weed of cultivation but now strongly declined due to changes in agricultural practice and only rather thinly scattered, mostly on heavier boulder clay soils. Flowers July to September. Leaves green with segments that are a little broader than those of the mayweeds. Flowerheads solid inside at the base with the central disk not elongating at maturity. Flowerhead scales present towards the centre of the flower disk, narrow. Phyllaries green in the centre with whitish margins and with white hairs. Seeds with eight to 11, bumpy ribs and without resin glands. Foliage unpleasantly scented.
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Scentless Mayweed (left) |
narrow flowerhead scales |
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Austrian Chamomile Cota austriaca
Introduced annual. This species has started to appear in artificial sowings of 'wildflower mixes' on field margins and on undeveloped corners in urban areas. Flowers May to August. Leaves usually with rather dense, whitish hairs, giving them a grey-green look. Flowerheads solid inside at the base with the central disk not elongating at maturity. Flowerhead scales present in the yellow flower disk, becoming rigid, almost prickly, as the seeds develop. Phyllaries green in the centre with whitish margins and dense, white hairs. Differs from Corn Chamomile in its slightly neater looking, more closely lobed leaves and its marginal seeds, which are dorsiventrally compressed with two, main marginal ribs. Foliage pleasantly scented.
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Corn Chamomile Anthemis arvensis
Introduced annual. Once a widespread weed of cultivation but now strongly declined due to changes in agricultural practice and only rather thinly scattered, mostly on light, sandy soils. In recent years, this species has been included in 'wildflower mixes' and may be found in sown conservation strips along with poppies, Cornflower, Corn Marigold and Corncockle. Flowers May to August. Leaves usually with rather dense, whitish hairs, giving them a grey-green look. Flowerheads solid inside at the base with the central disk not elongating at maturity. Flowerhead scales present in the yellow flower disk, a little broader than those of Stinking Chamomile. Phyllaries green in the centre with whitish margins and dense, white hairs. Seeds with nine to 10, smooth ribs and without resin glands. Foliage pleasantly scented.
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Sicilian Chamomile Anthemis punctata subsp. cupaniana
Introduced perennial. Rare as a garden escape or throw-out but well-established at a few locations in East Suffolk. Flowers June to July. Leaves with a dense covering of whitish hairs, giving them a silver-grey look. Flowerheads solid inside at the base with the central disk not elongating at maturity. Flowerhead scales present in the yellow flower disk, with a three-pronged, dark brown tip. Phyllaries green in the centre with brown margins. Seeds smooth, only slightly ribbed and without resin glands. Foliage lightly scented.
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Common Chamomile Chamaemelum nobile
Probably occurred formerly as a native on acid soils but now a rare plant, occasionally found as an introduction or garden escape. A perennial which can be mowed and kept low and sometimes grown as a 'chamomile lawn'. Flowers June to July. Leaves green with relatively short and stout segments. Flowerheads solid inside at the base with the central disk only elongating a little at maturity. Many curved flowerhead scales present in the yellow flower disk. Phyllaries green in the centre with whitish margins. Seeds angled but not ribbed and without resin glands. Foliage pleasantly and strongly chamomile scented.
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