Goldenrods
What are they?
The goldenrods are members of the daisy family (Asteraceae). The small, usually golden-yellow, florets are typically arranged in clusters along the upper parts of the stems and form spreading flowerheads that are often multi-branched and contain a large number of indiviual florets. Each bears the typical daisy family appearance, with each floret having five tiny petals that are fused into narrow tubes. Clusters of these florets are then contained within a sheath of phyllaries. Goldenrods are particularly common in North America, where a great many species have evolved and a number have been introduced to the UK as garden ornamentals.
Where are they found?
Our one native species is a scarce plant of grassy places on acid soils, while other species are occasionally encountered as garden throw-outs. The two larger species have the potential to be rather invasive as they can spread to form quite extensive colonies in open, grassy places and can persist for many years.
Identification
Goldenrods are all rather similar in their flowers, so are best identified by taking note of the overall appearance of the flowerhead (especially whether branched or not) and details of the leaves and stems. Note that the overall shape of the flowerhead can change somewhat according to the stage of development of the flowers. After flowering, all species produce the 'fluffy' clusters that are so typical of the Aster family.
European Goldenrod Solidago virgaurea
Native. Uncommon in East Anglia and found in a scattering of grassy places on acid soils and heaths. Flowers June to September. A short species, to a metre in height and often much less. Larger plants have branched flowering spikes but small plants often have just a single stem. Leaves relatively small, 2-10cm in length and often strongly curled. Stems with a mix of short, curled, glandular and simple hairs.
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Canadian Goldenrod Solidago canadensis
Introduced from North America as a garden ornamental and widely established on rough ground and grassy places. Often discarded by gardeners as it can become overly dominant in a garden. Flowers August to October. A tall species, 1-2.5m in height. Flower spikes much branched and openly spreading. Leaves relatively large, 4-8cm in length. Stems ridged and with a varying amount of short, curled, simple hairs.
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Early Goldenrod Solidago gigantea
Introduced from North America as a garden ornamental and scattered in the region on rough ground and grassy places. Often discarded by gardeners as it can become overly dominant in a garden. Flowers July to October. A tall species, 1-2.5m in height. Flower spikes much branched and openly spreading, though branches are typically shorter than those of Canadian Goldenrod. Leaves relatively large, 4-9cm in length. Stems only lightly ridged, hairless and typically with a whitish or glaucous 'bloom'.
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Rough-stemmed Goldenrod Solidago rugosa
Introduced from North America as a garden ornamental and once recorded in Suffolk as a garden escape or throw-out. Flowers August to October. A short species, to 1m or so in height. Flower spikes openly spreading but typically wand-like and unbranched. Leaves relatively small, 3.5-9cm in length, with strongly impressed veins. Upper stems with a good covering of stiff, whitish hairs.
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