JARS v48n2 - The Genus Trillium: A Neglected Companion

The Genus Trillium: A Neglected Companion
Gordon Collier
Taihape, New Zealand
Article first appeared in the Portland Chapter newsletter. Several additions have been made for publication in the Journal.

In the first catalogue I ever possessed some 35 years ago, this strange plant - trillium - was listed. My interest was immediately aroused and I rejoiced in the beautiful plant the nursery sent me.
A stumpy underground root stock sent up a slender stalk topped by three leaves bearing three sepals and three snow-white petals. A trillium! Intrigued, my further reading revealed that this is an ancient member of the lily family occurring in the wild from the Himalayas, east across Japan to North America. Of the 50 or so recognized species, the majority come from the latter, also the most garden-worthy.
This early interest in trilliums has continued all my gardening years, slowly building up a collection of some 20 species and varieties to grace my spring garden. ¹ Acquiring these in the Southern Hemisphere has not been easy as there are few sources of supply in my country and many eager enthusiasts waiting to pounce.
Growing trilliums from imported seed has proved totally frustrating. Not only do we have to contend with the plant's natural dormancy, but we also have to contend with the delay in shipping from the Northern Hemisphere. Seeds invariably arrive totally dried out - germination then can take five years, but mostly this does not have to occur. If the various societies handling trilliums were to hold and pack more suitably, this might improve.
It is usual for seeds of the tiny Trillium rivale to germinate in the first season after sowing, and in most other species fresh seed will yield some germination, making a lie of "double dormancy." One trillium authority tells me there is no such thing. This autumn a friend gave me a large pot in which he had sown fresh seed of T. chloropetalum . By mid-winter every seed had germinated, and the pot was a veritable forest of new leaves.
Importation of live plants was the other possibility, and in 1962 on a visit to England, I bought a number of precious species from a firm in Surrey. The vision of huge boxes of trilliums remains vivid in my memory; dried and shriveled, had they been dug in the wild and then imported? Hopefully not. This first importation proved very successful, traveling in the vegetable locker in the MS Ruahine, a six-week voyage!
Later consignments have come by air. Thus was acquired the exquisite double form of T. grandiflorum 'Snow Bunting' from the Savill Gardens. On my most recent trip to your country, I located a source of the double form of T. ovatum 'Edith'. Hopefully this will prove as delightful as its namesake in Graham, Washington.
In New Zealand, import and quarantine restrictions make life very difficult both for the plant and the importer. Once a good friend brought me a precious collection of trillium species, all documentation in order, only to find that the agriculture inspector on duty did not know the difference between the terms lilium and Liliaceae . The whole consignment was redirected and lost en route.
Despite these difficulties, my plants continue to thrive. They seem to be very tolerant of both wet and dry conditions, but the optimum lies somewhere in between. Our central North Island garden at an altitude of 1,400 feet receives 40 inches of rainfall per annum. Snowfalls are rare and frosts not severe. This seems an ideal climate as most trilliums have set seed before the drier months commence - February and March.
Trilliums do not need elaborate cultural requirements; in fact, here they survive considerable neglect in very heavy clay soil. They are certainly best left alone once planted, and remember not to walk across a planting even when the plants are supposedly dormant. Like lilies, they shift best just after flowering; I haven't plucked up courage to shift in flower yet. Walking on a patch usually damages the growing "shoots" and results in malformed leaves next spring. Unless I have hand pollinated flowers, the seed is allowed to fall where it may. The birds usually help. It is exciting to see seedlings popping up in unexpected places. If the weather is wet at flowering time, little seed will be set unless hand pollination is carried out. Often plants will remain infertile unless a new clone is used as a pollinator.
Trilliums associate beautifully with rhododendrons and look even better where ferns, hostas, rodgersias, astilbes, irises, uvularias, convallarias and actaeas are included. These are very happy companion plants in every rhododendron garden and we wouldn't be without them.
So it was after many years that overseas visitors started to find their way to our garden. My first American was set upon as soon as possible as a source of information on trilliums, or better still, seeds. My mortification was complete when it was revealed my quarry knew nothing on the subject. He held a Ph.D. in pomology. Subsequent visitors have not escaped quizzing, and some have proved helpful. The hunt never gives up!

In New Zealand, T. grandiflorum is not widely grown although it is extremely beautiful. Seed set of this species is here very meagre. Some day, someone will send me a bag full of juicy ripe seeds and these will produce billowing fields of young plants bursting with snowy white blooms - such dreams!
Fortunately T. chloropetalum is widely grown in New Zealand and a very vigorous plant in our conditions. Cecil Smith [Newberg, Ore.] kindly sent me seed from his garden in 1981 and this resulted in flowers five years later. Thus we saw the "green" form for the first time as well as his very superior "red" form.
Trillium vaseyi flowers very well here too. Deep maroon, very large and flowering late in the season, the flowers hang beneath a parasol of leaves. We also grow a large deep yellow and very vigorous clone of T. luteum , thanks to our friends, the Kolaks of Portola Valley, Calif.
New Zealanders are just as confused over the identity of T. chloropetalum and T. sessile as the English, where even well known horticulturists are out of step in their writings. Yet T. chloropetalum which comes from the west [western U.S.] is larger in every part than T. sessile from the east [eastern U.S.] and is never white.
Trillium decumbens is a particularly fascinating species from Alabama and Georgia; the flowering stem lies flat on the ground, and the dark purple-red flowers look so unusual backed by the ruff of spotted leaves. The Midwestern species T. nivale is very rare in New Zealand and almost unknown in England. Our own plant is vigorous producing five flowering stems this spring (September 1992) after two seasons. But will it set seed? One last species that grows strongly here, from Illinois and Missouri, is T. viride . Greenish elongated "petals" set this one apart.
It is strange that as a New Zealander living on the far side of the Pacific Ocean you should ask me to write about your native flower. Yet in my brief travels in your country, I did not see many trilliums used in rhododendron gardens or any other for that matter. The Cecil and Molly Smith Garden leads the way for all of us.

Reference
Trillium Genus , Kazuko and Junichiro Samejima.

¹ Trilliums at Titoki Point Garden & Nursery: Trillium catesbaei , cernuum , cernuum var. macranthum , chloropetalum , cuneatum , decumbens , erectum , erectum forma inteum , erectum var. album , grandiflorum , grandiflorum 'Snow Bunting', luteum , nivale , rivale , ovatum , recurvatum , sessile , undulatum , vaseyi and viride .

Gordon Collier is owner of Titoki Point Garden & Nursery in Taihape, New Zealand. He will be a featured speaker at the 1995 ARS Annual Convention in Portland.