National Council for The Conservation of Plants and Gardens
National Collection of the Genus Codonopsis and Allied Genera
A problem frequently encountered with Codonopsis is that of mis-identification but hopefully this website will start to put an end
to that. We have lost count of the number of times that we have acquired plants or seeds of “C.ovata”, for instance, only to find
that it is really C.clematidea. Many seed lists will have species such as Cc ovata, bhutanica, mollis, meleagris, convolvulacea or tangshen that invariably are something different and more readily available. We now seek out specialist seed lists from collectors of seed in the wild if we can.
Unfortunately many nurseries exacerbate the problem by offering young seed raised plants for sale from the same seed lists. We have discovered several instances where descriptions and/or photographs have been taken from the internet without any attempt to ensure they are correct. One aim of this website is to try to correct this problem and break the vicious cycle.
Where we have collected seed from our own plants we have included details in the plant’s description but typically it is brown and oval shaped measuring approximately 1.5 x 0.8 mm. The seed of C.lanceolata is very distinctive being large, straw coloured with a “wing” attached, yet closely related C.ussuriensis has black rounded seed.
Seed can germinate in one of two ways. Epigeous germination is where the cotyledon rises above the ground and becomes the seed leaves often taking the seed case with it. Hypogeous germination is where the cotyledon remains below ground as a food store and a shoot appears above ground with initially small first leaves that grow to full size. Hypogeous germination is much less common amongst Codonopsis, examples being Cc lanceolata, ussuriensis and Pseudocodon convolvulaceus ssp. forrestii.
A few species have seed leaves that are longer in proportion to their width and on longer petioles than normal, examples being Cc bulleyana and thalictrifolia.
The shape of the tuber will be either sub-spherical or the more typical carrot shaped, often branched or divided. The latter can grow quite large and are therefore much less suited for long term pot culture but the former are quite suitable. Where we have had the opportunity to examine the tubers we have included details in plant descriptions. Codonopsis gracilis does not have a true tuber but grows very fleshy swollen roots that can be used for taking root cuttings.
As stated previously C.clematidea is at the heart of many cases of mistaken identity. One easy way to identify it is by its calyx lobes which, when in bud, totally enclose the flower. As the flower develops the calyx lobes will split open and curl upwards to reveal the opening flower. This is quite common amongst the climbing species but appears to be specific to C.clematidea amongst the non-climbing species currently in cultivation. In other non climbing species (e.g. Cc obtusa, ovata, cardiophylla ) the calyx lobes are separate even at the early stages of the bud’s development.
C. pilosula ssp tangshen is another commonly mistaken plant (it is usually Cc pilosula or bomiensis syn. rotundifolia var. angustifolia ) but it is easily identified by its inferior calyx see our individual description.
There is also significant confusion amongst the species that make up the genus Pseudocodon i.e. those twining climbers with blue or white saucer shaped flowers but the three most frequently encountered are P. grey-wilsonii with its large blue flowers with a hairy purple ring, P. convolvulaceus ssp. forrestii usually later flowering with a dark purple centre to the blue flower and P. vinciflorus ssp. vinciflorus with its smaller blue flowers. This latter species is different in bud to the others as the calyx lobes separate very early in development
We hope that the above notes help to identify your plant before it flowers but please see our individual descriptions which are mainly based on our experiences in growing and sometimes losing these delightful plants. We would like to place on record our thanks to the previous National Collection Holder, Paul Kneebone, who was so patient and helpful in our early Codonopsis growing years and upon whose notes we have leaned heavily for the whole of this section.