In horticultural parlance, this is considered a “double-flowered form” of western trillium. As noted by Ron B in response to silver_creek's photograph of this same plant at UBC Botanical Garden in this discussion thread, double-flowered trilliums are indeed uncommon, to the point where no named cultivars were known to exist by the authors of a book on the genus. This cultivar predates that book by at least twenty years, but seems to have slipped into obscurity. With the exception of the photographs and discussion on the UBC BG web site, there are no other mentions of it online. Perhaps it has only ever been in the collections of two institutions: UBC BG and the Washington Park Arboretum, the source of the material here at UBC.
An understanding of double-flowering manifestations is continuing to build. It has long been recognized that double-flowered forms are the result of mutated floral organs, e.g., stamens developing as petals. However, the genetics of these transformations, such as which genes are at least partly responsible, has not been well understood until recent years. I'll have to track down the paper this media release is based on, but for now, please read Genes for Unusual 'Flower Within a Flower' are Identified by UCSD Scientists.
Double-flowered trillium have a long history. The history began with the 1864 record of a double-flowered Trillium grandiflorum taken from the wild into a garden. Since then doubles have been recorded in T.erectum, T.ovatum and some sessile trilliums. A problematic record of a double T.vasyii exists, but the plant is no longer known to be in cultivation.
In addition to doubling caused by "normal" genetic mutations, it can be associated with a diseased state - both viral and mycoplasmal.
A historical study and search for the wild origin of cultivated forms is available in: ROCK GARDEN QUARTERLY, vol. 59#3, Summer 2001 - Double Trillium: History of an Elusive Flower by John and Janet Gyer. The work was also published in THE GREEN SCENE, the magazine of the Pennsylvania Horticultural Society, November 1997. Three named forms of T.ovatum were found during this historical research 'Edith', 'Barbara Walch', and 'Kemoor'.
Ah, I should have mentioned double-flowered western trilliums to be a bit more specific when stating how uncommon they are re: cultivars.
For those locals interested, a double-flowered trillium, Trillium ovatum 'Plenum' will be available at next week's Collectors' Plant Auction.
Hi, I was wondering, do trilliums only grow under douglas fir? I read this online, and am wondering if anyone has had success growing them without douglas fir. The botanical name is Trillium ovatum. Thanks!
Yes, Trillium ovatum (T. o. will grow without Douglas firs present. At home, we have a trillium I rescued as a seedling from among grasses on our lot. It is growing beside a Viburnum x bodnantense 'Dawn' and in front is a Daphne laureolum (an invasive companion for Vinca major as seen on the BPoD)The native tree cover on our lot was western red cedar(there are cedar roots where our trillium grows) & bigleaf maple. I have seen it growing in a forested park setting, among red alders--although one can make a case that this habitat was once Douglas fir forest. A neighbour has many western trillium planted on the north-side of his house between the house foundation & the sidewalk. A preferred requirement is part shade. Trillium tolerates drought well once established. At UBCBG, we have planted T.o. with native ferns & Mahonia nervosa (dull Oregon grape)--nasty common name!
Re. Double-flowered Trillium by John: the accepted name for T.o.'Kemoor' is T.o. 'Kenmore'. No time to do further research. Thanks for the memory jog! I haven't seen 'Kenmore' & 'Tillicum' side by side in the Garden in 30 years!
Patricia Gooch et al check out Darlene O'Neill's 1995 UBC MSc (Plant Science) thesis "Taxonomic Study of Trillium ovatum forma hibbersonii" at https://circle.ubc.ca/bitstream/2429/4187/1/ubc_1996-0076.pdf because Darlene lists forest zones (p. 9 "Distribution and Ecology) and "Collection locales" Table 1, p.10 where Trillium ovatum (straight species) grows.
Forest zones: Coastal Western Hemlock, Coastal Douglas fir, Interior cedar-hemlock, Interior Douglas fir, near streams in Ponderosa pine & lodgepole pine; also in (Sequoia sempervirens) Coast redwood forest communities. Found as far east as south-eastern Waterton Lakes Park, Alberta. Thanks, Darlene! Darlene was mentored in her thesis subject by Gerald B. Straley (deceased), a former Curator of Collections for UBC Botanical Garden. Anyone seen Darlene recently? Say Hi!