Conserving Annuals and Biennials

The National Council for the Conservation of Plants and Gardens (NCCPG), a registered charity, was formed some eight years ago following a Conference organised by Christopher Brickell, the then Director of the Royal Horticultural Society's (RHS) Gardens at Wisley, and now Director General of the RHS., to study the urgent problem of the disappearance of an ever increasing number of our garden plants. The main aim of the NCCPG is to conserve those plants worthy of preservation but it is not the aim to conserve anything at any cost.

Since the beginning it has built up a network of over 300 National Collections of plants ranging from Aster (Michaelmas Daisy) to Galanthu Sy Rheum and Zeikova distributed throughout various parts of the country and among a wide variation of organisations from Botanic Gardens and National Trust Gardens 30%, Colleges and Schools 13%, Local Authorities 10%, Nurseries 10%, private individuals 32% and local NCCPG and horticultural groups 5%.

These collections go a long way to ensuring that both old and new species, varieties and cultivars have a chance of survival. The collections must be kept well documented and maintained, with the collection holders, allowing access where possible and also providing material for research to Wisley and other scientific establishments as well as to collection holders and on occasion to nurseries.

In most cases, the National Collections, which normally concentrate on cultivated varieties (cultivars), supplement the holdings of the major botanic gardens which in the main concentrate on wild species. The NCCPG decides through consultation with various groups and eminent horticulturists those plants that need conservation based on aesthetic, historic, genetic and commercial importance.

We must ask ourselves how many garden >plants were grown years ago and how many can be seen around today; I would say only a fraction. Paeonia for example. Since the 1800s some 800 species, varieties and cultivars have been recorded in literature but less than 20% have been available in recent years.

Some 250 different snowdrops have been recorded in literature but less than 25% available in recent years. The Single Rocket (Hesperis matronalis) is easily propagated by seed but the double forms have to be propagated by cuttings of the flowering stalks. There is a double white form with 2ft (60cm) spikes, a dwarfer form, a pink form and a purple. None of these is offered commercially and they are now in very few gardens, or are they? They used to be most common in Scotland. Since the 17th century many cultivars of hollyhocks of various types have been grown. Some two hundred years later we had cultivars like 'Willingham Defiance' which was awarded a First Class Certificate in 1864, 'Black Prince' and others, but then in the 1860s and 70s a bad outbreak of Hollyhock Rust took its toll. What happened to these cultivars and many others - are they still surviving somewhere?

The National Collections contain some three hundred collections with only one or two of annuals including the collection of annual poppies at Thompson & Morgan. Why, is it the hard work? Trees and shrubs need little care after planting, herbaceous plants require a little more work but with annuals and biennials a lot or work is required. Seeds must be sown in spring or early summer, the flowers must be assessed for trueness to the original characteristics of the variety. Then the seeds must be collected in the autumn for saving, cleaning and storing in appropriate conditions ready for re-sowing the following spring.

When we are talking about annuals and biennials we basically need to talk of two groups, the species and the cultivars. With the species we can normally say they will come true from seed - subject to the normal seedling variations, which gives so much of the variation one is used to seeing. With cultivars the majority of F1 hybrids do not come true from seed but tend to revert to the features of their parents. But the ordinary, open pollinated cultivars do come true from seed. Plants are like music and clothes, today they are in, tomorrow out, but it must be remembered that seed must be collected. An example of this is Cosmos atrosanguineus, a perennial plant which, because of its susceptibility to frost, was raised from seed each year. Seed originally coming to this country in 1835 and the plant was awarded an Award of Merit in 1938. Since then it has been almost lost to cultivation and only kept going by propagation from cuttings - the plants we have now appear to be sterile, which is certainly not the case in the upland regions of Mexico where it is native. It is now showing a comeback and is listed as being available from one or two nurseries so the fashion is in again for Cosmos. But if a fertile form were found, over-wintering in frost free conditions would be unnecessary and it could also be used to breed new varieties.

I am including a list of a few annuals and biennials which it would be worth seeing more commonly grown; one or two of the plants are monocarpic plants (which flower once in their life and then die) and a perennial which, because of cultivation problems, is also treated as an annual, this is the lovely Ostrowskia magnified. If anyone is growing any of these plants I would be grateful if they would write to me at NCCPG, RHS Garden, Wisley, Surrey GU23 6QB, U.K. For details of how to join the NCCPG write to the same address.

Vanishing plants

The NCCPG feels that these plants are in danger of disappearing from cultivation and deserve to be grown much more.

Alonsoa acutifolia. var Candida. Bushy, slightly woody plant usually grown as an annual pot plant with broad, sharply toothed foliage and white flowers with a yellow centre. 2ft (60cm).

Amelias annuus. Small annual with pretty l½in (3cm) blue daisy flowers whose petals curl under in all but warm weather.

Campanula celsii. Hairy, ash-grey biennial with ascending or slightly floppy stems and velvety blue, tubular or bell shaped flowers.

Campanula lingulata. Hairy, erect plant with six to nine narrow, tubular blue flowers. Dies after flowering.

Campanula mirabilis. Long fleshy root-stock producing a flat rosette of long leaves and hairy, pale lilac, bell shaped flowers. Dies after flowering.

Campanula primulaefolia. Biennial with angular stems 2ft (60cm) high and dense spikes of funnel shaped purple flowers lightening near the tip.

Campanula speciosa. Dense rosette of narrow leaves up to 18in (45cm) across and purple or blue flowers on 18in (45cm) stems. Dies after flowering.

Cosmos atrosanguineus. Half hardy tuberous perennial with dark blood red flowers. Infertile form common, fertile form rare.

Gilia rubra. Biennial with fine foliage and upright spikes of bright red flowers.

Nemesia azurea. Blue-mauve flowers on 1-2ft (30-60cm) stems with lance shaped toothed leaves.

Nemesia barbata. Well branched annual with four angled stems and 4in (20cm) heads of flowers, the upper lip white and lower lip blue with red and purple lines.

Nemesia versicolor. Upright annual with oval to lance shaped leaves and short spikes of blue-lilac or yellow and white flowers.

Ostrowskia magnified. Dramatic perennial usually raised from seed reaching 4ft (1.2m) with large sky blue trumpet shaped flowers.

Papaver glaucum. (Tulip Poppy) Erect annual reaching 18in (45cm) with four to six bright scarlet tulip-like flowers on bristly stems.

Papaver horridum. Grows to 3ft (90cm) with yellow prickles and 12in (30cm) leaves with prickly tips. Small reddish orange flowers.

Papaver triniaefolium. Biennial reaching 12in (30cm) with long-haired stems and smooth leaves making an attractive rosette. Flowers pale red, 1in (2.5cm).

Sedum formosanum. Smooth, rather floppy half hardy annual with reddish branches and yellow flowers.

Sedum hispanicum. Hairy, pinkish well branched annual or biennial with white flowers, each petal lined with red.

Sedum annuum. Tiny tufted annual with minute leaves and small yellow flowers.

Tropaeolum azureum. Smooth climber with small tubers, five lobed and rather variable blue flowers.

Graham Pattisson is Deputy General Secretary of the National Council for the Conservation of Plants and Gardens.

Source of article
Growing From Seed - Spring 1987 Vol. 1 Number 2
© The Seed Raising Journal from Thompson & Morgan