Umbellifers 1: Smyrnium

The glorious golden-green of Smyrnium perfoliatum - beautiful but dangerous.

 Early summer is a peak time for many members of what I call Umbelliferae but more modern types think of as Apiaceae, though both are regarded as valid names for the family. This is the first of a perhaps irregular series of posts about some of the garden-worthy umbellifers.

S. perfoliatum

Many gardeners (including myself) find the golden-green flowers and bracts of Smyrnium perfoliatum extremely attractive and go to some trouble to grow it. At least, I often hear that people have trouble with it, as that as not been my experience, and it can be very invasive. References often say that it is a biennial, but this isn't true as it in fact takes several years to flower from seed. In the first year only a pair of cotyledons appear above ground, producing a tiny subterranean tuber. In subsequent years this produces an increasing number of normal leaves, but will not flower for 3-4 years after germination. It looks great in the border and especially in dappled light under trees, as for example at Colesbourne Park (see below), but we cut off all the stems after they've flowered to prevent it reseeding. One or two will be missed and thus provide moderate continuity, but mass seeding is just a menace. Luckily each plant dies after flowering so it can be kept in check if diligently dead-headed.

Smyrnium perfoliatum in the wood at Colesbourne Park.

In the cottage garden I grow a different species, S. rotundifolium, from seed collected on Mt Olympus, where I've seen it colouring wide areas gold in early July. It is actually not quite as spectacularly yellow-green as S. perfoliatum as the bracts do not go so yellow, but it is still attractive and worth growing. It behaves in exactly the same way as its cousin and I think the same precautions are advisable.

Smyrnium rotundifolium

S. rotundifolium with Myosotis sylvatica in thecottage garden, May 2012.

The two species are native to southern Europe, with S. perfoliatum having a huge distribution from Portugal to Romania, while S. rotundifolium is more Mediterranean. They are quite easy to distinguish (when in flower), as S. rotundifolium has rounded, more or less untoothed leaves and bracts and a smooth but slightly ridged stem. The leaves and bracts of S. perfoliatum are strongly toothed, and the stems have distinct membranous wings. There are also differences in floral and fruit characters

S. rotundifolium: rounded leaves without teeth, and a smooth or slightly ridged stem.

S. perfoliatum: triangular leaves and bracts, with distinct teeth, and conspicuously winged stems. The leaves are perfoliate in both species (i.e. the stem appears to pass through the leaf).

Smyrnium olusatrum in Devon, May 2010

A third species, S. olusatrum, Alexanders, is occasionally cultivated, but is better known in Britain as a coastal wildflower: it is wintergreen and somewhat tender, so flourishes best in areas where frost is slight. It is a bit coarse for the garden, although not entirely unattractive when in full flower, and the glossy foliage is nice in winter in mild conditions.