Plant of the Month for November, 2011

Clematis columbiana v. tenuiloba

(KLEM-uh-tiss man-SHEU-ree-ka)

In his talk on the flowers of the Western United States, Barrie Porteous highlighted Clematis columbiana var.  tenuiloba.  Just  15 to 28 cm (6 to 10") in height, with a sprawling growth habit, and native to areas of limestone rubble and cold winters, it is a highly desirable species for Ontario rock gardens. Like other alpine plants, it thrives under high ultraviolet radiation and drying winds. ORG&HPS member, Barry Parker observed that the one he planted outdoors in a trough was superior to his greenhouse specimen. Former member Rodney Shaver had success growing this plant at the base of a crevice garden.

Clematis columbiana var. tenuiloba photo courtesy of Barrie Porteous

While the species flower is mauve, the selection 'Ylva'™ is darker and bluer. Henrik Zetterland of the Botanic Garden in Gothenburg named the latter after his daughter.

'Ylva' outside in trough

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Ylva' in bud in greenhouse   

'Ylva' photos courtesy of Barry Parker

Because it is challenging to get Clematis columbiana var.  tenuiloba to bloom in cultivation and obtaining viable seed is even more difficult, you will rarely find seed offered through our Seedex. Propagation from seed will produce plants identical to the parent species.  Seed should be sown while it is still fresh in a very well-drained medium, then placed outdoors over the winter. For those who like to tend their seed pots indoors, this species is one that will also germinate at room temperature without prechilling. Growth of the seedling is slow. Flowering can be expected in the spring of its second year and may continue into August.

Sources: Larry Davidson, member of ORG&HPS, carried the plant last season http://losthorizons.ca. Kristl Walek carried the seeds of this species last year at www.gardensnorth.com. She hasn't indicated whether it will be available this year.