SPECIAL EDITION: Woodland Poppies
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THE NEWSLETTER OF THE SHADE AND WOODLAND PLANTS GROUP December 2017 SPECIAL EDITION: Woodland Poppies Introduction The special edition last year focused on a single genus, Epimedium. This year it is dedicated to a single family, the Papaveraceae. It is an interesting family with many choice woodlanders. Corydalis and Meconopsis spring immediately to mind. To keep the subject within bounds we will limit the discussion to plants that are relatively easy to obtain and concentrate on growing and propagating the plants in the open garden. Members of the poppy family have a few features in common: they often exude latex when bruised or cut; the leaves are often lobed or divided; they are usually arranged oppositely, or occasionally spirally, around the stem; the flowers are either single or several along a stem and are either radially symmetric or with one or two planes of symmetry. Botanists divide the family into three subgroups. This division is also useful horticulturally and we will use it as a structure for our discussion. The first group have radially symmetrical flowers like a poppy (Papaveroideae). The second group has flowers with complex structures that have one or two planes of symmetry such as a Dicentra (Fumarioideae). The final group contains a single species, Pteridophyllum racemosum (Pteridophyloideae). This is thought to be the most primitive member of the family, looking more like a fern with flowers than a typical poppy. Covering the first group we have sections on Meconopsis, plants that used to be in Meconopsis, other yellow poppies (Hylomecon, Stylophorum etc.), and bloodroot and snow poppy. Covering the second group we have sections on Corydalis, Dicentra (including Lamprocapnos), and Dactylicapnos. Finally there is a section describing Pteridophyllum. [Note: all text by Joe Sime except where indicated.] Meconopsis Meconopsis is a large genus containing many interesting plants, most of them challenging to grow. Since we decided to work on this "Woodland Poppies" issue, the AGS has published a 384 page volume "Meconopsis for Gardeners", edited by the author of the monograph of the species, C. Grey-Wilson. (ISBN 978-0-90004- 899-9). This is a very thorough exposition describing all the cultivated species and hybrids with details of cultivation and propagation techniques and lots of excellent photographs. If you are a serious lover of the genus then I recommend that you buy this book, although you may need a second mortgage! In this section I will simply limit myself to describing how the ordinary woodland gardener may grow big blue poppies and M. napaulensis (hort). To do this we will need to understand a little about these plants. They come from woodland and meadows in the Himalaya, where they enjoy cool, humid summers with ample rainfall and cold dry winters. Their first requirement is determined by how they spend the winter. The big blue poppies have resting buds just below the surface of the soil, and "napaulensis" types have a crown of leaves that remain evergreen over the winter. In both cases they will rot if exposed to excessively wet or waterlogged winters. Their second requirement is determined by the fact that they are both accustomed to a relatively deep, humus and nutrient rich soil. Both of these requirements can be met by building up a slightly raised bed of open soil, rich in garden compost. The third requirement is for a cool, humid and moist summer. If you are lucky enough to live in the northwest of the UK, then nature will supply this for you most years, but the further south and east you live the more you will have to provide this yourself. You should select a site that is sheltered and well-shaded, but not densely so. There should certainly be no harsh midday sun. If the site is in easy reach of a tap, and if water is not too expensive in your area, then it is worth putting in a watering system. Grey-Wilson recommends misting nozzles as, for a relatively small amount of water, they will also increase humidity and lower temperatures. If, as in my case, the site is a long way from a water supply then in long, hot summers it is difficult to get enough regular moisture out to the plants and I have to accept that, in those years, I will have significant losses. The big blue poppies may become monocarpic, and the napaulensis types may rush to flower and set seed before they are ready. The solution to this is produce new plants annually. In my opinion the spectacle of these beauties performing in the good years is worth the occasional disaster. As they are monocarpic, maintaining a population of "napaulensis" requires that you grow some annually from seed. Likewise to insure against losses, it is cheaper to have a constant supply of seedlings of the big blue poppies. Thus we need to know a little about seed production and germination in Meconopsis. Meconopsis are essentially self-sterile. The pollen of one clone usually cannot germinate properly on its own stigma. This is not an all-or-nothing issue. Occasionally self-pollination occurs. But if you want a decent crop of seed you will need more than one clone. The issue is further complicated by the fact that they can produce a mass of sterile ‘seed’, so fruits will swell and produce something that looks like seed even if not pollinated. Often both fertile and sterile seeds are produced in the same pod. If the ‘seed’ is relatively small, distorted and shrivelled then it is sterile. Seed has a relatively short viability. Our preference is to sow it immediately it is ripe. However if you have problems in overwintering the young plants, sowing can be delayed to spring if it is well-cleaned, dried and stored in an airtight container in the fridge. Germination of commercially supplied seed is likely to be poor (but not zero!). The seedlings are very susceptible to damping off so should be sown thinly. They also require some light to germinate so cover with only a thin layer of compost. There is some debate about when to prick out, ranging from immediately the cotyledons are established, to once they have 2 pairs of true leaves. This is because there are competing problems of root damage and damping off if they are left too long, and damage to the delicate leaves if they are handled too soon. We tend to prick out late… but if you are careful it probably does not matter. Seed sown in the summer of one year should be ready to plant out in the spring of the next year. You may have noticed that unlike most articles in Shade Monthly we have got through a couple of pages and still not talked about species. This is because meconopsis are promiscuous and all the plants and seed, except those obtained from specialist suppliers, are hybrids that have arisen from interbreeding between species introduced to cultivation many years ago. This is why I have been steadfastly referring to "big blue poppies" and "napaulensis type". Unless you are, or wish to become, a specialist, there is no point in trying to maintain populations of the species. The hybrids can look just as good. Napaulensis (hort) covers a diverse range of plants, all hybrids with several different monocarpic, rosette- forming species in their ancestry. Grey-Wilson suggests naming this complex as M. x complexa. The Plant Finder is still calling them "napaulensis misapplied". Whatever the name, they are all monocarpic rosette formers taking from two to five years to flower. The leaves can vary in the degree of division, colour and density of hairs. Some form quite beautiful, felty, golden-haired mounds up to a metre across, and are worth growing for the leaves alone. The flowering stems can be more than 2 m in height and carry many flowers, which can be white or light yellow through to gold, pink or red. If you have friends that grow them then beg seed of good forms. Otherwise buy several different looking young plants from nurseries or garden centres. You should add new plants to your patch each year to eventually have a continuous show. Once they are established, collect seed from your best forms and produce your own plants. The situation with the "big blue poppies" is even more complex and the Meconopsis Group has spent several years sorting them out. They have divided them into three broad sections. (1) The George Sheriff Group. This is a group of mainly named hybrids characterised by being later flowering than the rest and having reddish tinges to the young leaves and broad seed capsules. However they are mostly, but not exclusively, sterile. (2) The Infertile Blue Group. This is a large group of mostly named hybrids that produce no fertile seed. (3) The Fertile Blue Group. This is also a large group of named hybrids, all of which are fertile and, of course, of their many un-named progeny. Most of their offspring do not necessarily resemble the parents, but ‘Lingholm’ is an exception, and now most plants seen under this name are seedlings closely resembling the original. For the general gardener, and particularly those unable to supply reliable summer moisture, I would recommend that you start with seed from plants of the Fertile Blue Group. Once you have reasonable success with these then it may be worthwhile buying some named varieties of this group to "pep-up" your gene pool. There is an excellent description of all these in ‘Meconopsis for Gardeners’. One nursery recommends that you do not allow a new plant to flower in its first year.