The genus Paris consists of around 24 species of flowering herbaceous plants found in temperate mixed forests. It has a wide distribution, from Iceland to Japan, with the greatest concentration being found in China. All have simple, erect stems with leaves arranged in a terminal whorl above which sits a solitary flower. The popularity of this genus is mirrored by its increasing availability, with 27 species and subspecies being listed in the RHS Plant finder alone. (Right: Our native Paris quadrifolia)
A member of the Trilliaceae family, formal classification of the genus Paris has seen several reviews, the most recent being that of Dr Li Heng (1986), where he proposes two subgenera – Paris and Daiswa. Later molecular evidence (Farmer & Schilling 2002) shows that the subgenus Paris should be further split into section Paris and section Kinugasa. It is worth noting that all three Taxa are commonly used at the Generic level ‘in the trade’ so you may well find Paris quadrifolia; Daiswa luquaensis and Kinugasa japonica listed.
Daiswa and Paris look superficially the same but are separated out by the fact that the former has an ovary with only 1 chamber with the seeds attached to the sides of it and the later having at least 4 chambers, with the seeds attached only at the centre. Kinugasa is easily recognised by its petaloid sepals which are white
Outdoor culture should consist of a deep well-drained woodland or humus-rich soil, preferably neutral to slightly acidic. A somewhat shady position that remains moist in the summer suits them best. The genus as a whole resents transplanting and plants are best left undisturbed where possible. Feeding should be given by way of a mulch of good quality leaf mould in autumn. Most species will take temperatures down to -100C if planted deep, this along with the mulch helps protect the newly emerging flower bud from late frost damage.
For pot culture, a compost comprising Loam; Leaf-mould and Gritty sand, opened up with a little fine bark or perlite suits most, if not all species. It should never be allowed to completely dry out, even during dormancy. The root system can be quite extensive and I have found that deep pots are best for those species which form thick, stout rhizomes. Amongst the subgenus Paris are some species which form fairly slender, branching rhizomes which for me do OK in more shallow pots.
By division: - As mentioned above, the rhizome of Paris can take on two forms; slender, branching (as in our native P. quadrifolia) or thick and stout (as in P. polyphylla). Propagation of the first type is fairly straight forward, the clump can be lifted, broken apart and replanted and as long as one is not too greedy one should expect a 100% success rate. Those that produce a thick, stout rhizome tend not to be at all generous when it comes to self-propagation; it then becomes necessary to give nature a helping hand. Observation of the related genus Trillium has shown that rhizomes that are mechanically damaged, by gnawing pests for example, have the capability to produce lateral growth buds around the site of the wound. This can be recreated in cultivation by deliberate means. By simply cutting a healthy rhizome in half and replanting both bits, the dormant ‘eyes’ on the back section are sometimes induced into growing. The method I have been most successful with (in terms of number of propagations produced) is to completely remove the terminal bud, soon after dormancy commences in summer – this can be a bit scary but it really does work. When the terminal bud starts into growth in the Spring it produces a hormone which inhibits side-shoot production, so removal results in dormant growths being activated along with the bonus of ‘pups’ being produced around the neck of the wound. It resulted in six new offsets on P. polyphylla for me and I now intend to try it on some of the rarer species.
From seed:- Best sown as soon as it is harvested, although, if preferred, it can be stored and sown in late winter or early spring, in a shaded cold frame. Seed can germinate relatively quickly, within 1 to 3 months with shoots being produced in the second year. Good air circulation is essential to prevent damping off. It is best to keep the young seedlings over-wintered in the cold frame, planting out, if desired, the spring following there emergence but note that some seed can remain ungerminated for a number of years. It has been reported that plants can flower in two years from seed but expect a 4 or 5 year wait.
Species to look out for are P.polyphylla, of which there are at least 10 subspecies. Flowering from late spring into late summer, it has a wide natural distribution – from the Himalaya, India and right across China. This is probably the easiest of the genus, either in pots or the open garden and is fairly easy to get hold of.
P. luquaensis is a member of the subgenus Daiswa and as such may be listed so. Whatever the name, it’s a real gem which should be sought out by the serious grower. From Luquan Xian of North-Central Yunnan, found growing at considerable altitudes in forest thickets, this species is definitely one for the pot as it doesn’t seem to have the strong constitution of the previous species and is still considerably rare in cultivation.
‘Kinugasa’ japonica (genus Paris, subgenus Paris, section Kinugasa – you can see why nurserymen usually refer to it simply as Kinugasa or Paris japonica!) which is endemic to Japan. Without doubt, the showiest of the genus, with its big white flowers which actually move, tracking the sun throughout the day. Mainly grown as a pot plant, due to the weighty price asked by most nurserymen but seems quite happy if kept as cold as possible, planted deeply in the garden. The picture on the left was taken at Gothenburg - there was also a fine plant in the AGS gold medal exhibit at Chelsea a couple of years ago.
If you can grow Trilliums in your garden and like ‘woodland’ plants in general, then the genus Paris is certainly one you should investigate more.