Shrubby Tasmanian clematis contributes to garden surprise

Most of the 200 species of Clematis are from the Northern Hemisphere. We have at least six native species in Australia, all but one vigorous climbers. That one is the scrambling shrub, Clematis gentianoides, from north-eastern Tasmania. It's also called the Bushy Clematis.

I didn't notice this species in flower when I was travelling through the north-east last spring but found it in full bloom outside the Tasmanian Museum and Art Gallery in their indigenous-plant garden. The next day I saw a cross between this species and the more common Mountain Clematis, Clematis aristata, in Royal Tasmanian Botanical Gardens - but I'll come to that later.   

As with most Clematis species, plants of the Bushy Clematis bear only male or female flowers. These flowers are of similar size and with mostly four, white 'sepals' (not technically petals but looking like them), although not uncommonly five or six. 

Male flowers have about 70 to 100 anther-bearing stamens and no vestige of the female sexual parts. The female flowers, however, have in addition to a similar number of carpels, 3-30 sterile stamens (called staminodes). So it's crowded inside these flowers.

Typically for dioecious plants - with male and female flowers on different individuals - there are usually more male than female plants. In this case not always a lot more - a study in 1976 found 53% of 659 seedlings were male. And occasionally a fertile female flower can be found on a male plant.

I believe all my photos show female flowers, with staminodes peeling back from the central clump. Feel free to correct me though!

The leaves of the Bushy Clematis are relatively thick for the genus, and as the species name suggests, a little like those of a Gentian. Apparently. Underground the species is also distinctive, with buried stems - rhizomes - extending the plant beyond the initial clump.

As to that hybrid in the Botanical Gardens, it was labelled 'Garden Surprise'. This cross between Bushy Clematis and Mountain Clematis occurs spontaneously in gardens, with the resulting offspring variable in form. You can see it is creeping a little in the photograph below.

Clematis 'Garden Surprise' (aka Clematis 'Southern Cross')

I gather the same cultivar is sometimes called 'Southern Cross', a selection from Tasmania registered in 1992. That registered cultivar is semi-deciduous and forms a 'mounding vine' - so halfway between the two species. I don't know if it has rhizomes and wasn't going to upturn this plant to find out.

Clematis 'Garden Surprise' (aka Clematis 'Southern Cross')