GARDENING - Oenothera proves promiscuous

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This large and bizarre family has proved to be promiscuous, says Val Bourne

I LOVE plants that change colour after they open, as evening primroses do. Choose carefully, and the days of late summer will be enlivened by large, translucent saucers of yellow and apricot, unfurling gently, basking in the sun, then growing richer in colour as they twist and close - only to be replaced by another flower.

This "creme caramel" sequence of pale and dark flowers can last well into October, and it makes this fragrant, moth-pollinated genus a garden must.

Oenotheras were brought to Europe from the New World, and have proved to be a particularly promiscuous family of plants. They have the unusual ability to produce offspring with a varying number of chromosomes, which makes them a taxonomist's nightmare and has resulted in a plethora of hybrids and subspecies.

There are 124 species of oenothera, including annuals, biennials and perennials. Between 30 and 40 are offered as garden plants. They are easily raised from seed, enjoy sun and relish poor soil.

Evening primrose oil is a well-known source of gamma linoleic acid (GLA), said to be a good dietary supplement for women in particular. The small drop of this nutrient in every seed serves as a readily available energy boost for the plant, allowing it to germinate and grow faster than its competitors.

This large and bizarre family has some antisocial members, best excluded from the garden. The bright yellow flowers of Oenothera biennis, which grow on sand dunes and railway embankments, self-seed mercilessly, so avoid it.

The invasive O. speciosa runs through the border and looks like an overblown bindweed in flower (most forms are pink). There are two white forms I would also discount: the scented but very lax sprawler O. pallida 'Wedding Bells' and O. acaulis alba, which bears enormous white flowers but produces seedlings that are doppelgangers of dandelions, only hairier.

However, there are two excellent seed-raised varieties that are widely available. Both are sensational in sunny borders, but treat them as annuals and save some seed.

O. 'Apricot Delight' is a perennial of upright stance that grows 2ft-3ft in height. It produces large lemon saucers 3in across, which darken and turn apricot as they wither. It is similar in stature and size to O. biennis, but has narrower leaves and warmer coloured flowers, and it is perennial in dry, sunny sites. O. versicolor 'Sunset Boulevard' is a short-lived perennial with smaller flowers in warm apricot deepening to red-brown.

There are prostrate oenotheras that tumble over paths and spill out of containers. O. macrocarpa has silvery-green leaves with a distinct silver mid-rib and large flowers, up to 4in across, in soft lemon. This trailing plant loves hot, dry conditions and performs for months. O. 'Greencourt Lemon' is particularly lovely.

The best-behaved upright perennial is O. stricta 'Sulphurea', which has cream-coloured flowers that darken to apricot, set against dusky foliage. This self-seeds in a well-behaved way, and makes several stems, reaching 2ft-3ft in height. The shorter O. fruticosa 'Fyverkeri' reaches 1ft-2ft and has brighter yellow flowers. Its foliage flushes red in hot, dry summers.

O. fruticosa subsp. glauca often has spotted leaves and produces lots of smaller yellow flowers from July onwards. Some forms are grown for their colourful spring foliage, and there is also a new German cultivar of O. fruticosa called 'Silberblatt', which has a rosette of darkly spotted silver leaves. But generally oenotheras are not great foliage plants.

Rather, it is their ability to surprise and delight - to pop up unannounced and generously unfurl those wet tissue-paper saucers in sunny colours - that I most admire.

Growing tips

Oenotheras love sunny conditions and well-drained soil. They are short-lived perennials and usually self-seed (often colonising newly dug areas of the garden) - but always save some seed as a precaution. Seeds can be sown in loam-based compost and germinate easily in warm conditions (65F-80F or 18C-27C). Seedlings take less than a month to appear. Spring sowing is most effective. Prick out seedlings individually into 3in pots, then plant out while they are still young - many plants have taproots that resent disturbance.

-- Anonymous, June 26, 2001


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