Thursday, November 5, 2009

The Three Petrocosmea minors - Part 3

A flowering plant of Petrocosmea minor veined leaf form. This form grows larger than any of the other forms, with heavier substance. Leaves and even flower petals show deeply incised veining along the central veins, lateral veins and even in between the lateral veins.

A close up photo the foliage of P. minor veined leaf form. Very glossy and bubbly in appearance, making quite an attractive plant in or out of flower. This form also seems to propagate the most quickly and readily from leaf cuttings and has the fastest growth rate of all the forms.

A close-up shot of the flower of P. minor veined leaf form, shows the recurved petals with the deep veining of the lower petals. Cymes are single to multiple flowered, with more branching of cymes on more mature plants. Cymes of this form have a sturydy, heavy substance.
The third form of P. minor in cultivation is the form now called P. minor veined leaf form. This form has been distributed as P. sp. '#5', P. sp. 'Chinese #5', and simply P. minor. It differs from the other forms most obviously in the deep veining of the large, heavy, glossy orbicular leaves. The petiole often has dense, quite long silvery hairs covering it, with these hairs being golden amber to brown near the base of the petiole. This form did succeed in a cross with P. sericea, using sericea as the pod parent. Seedlings of the cross can be seen in an earlier post on here a few days ago. The leaves of the seedlings do show the influence of P. minor veined leaf form, as they are all deeply veined even as small plants.

As new Petrocosmea species are collected and brought into cultivation, additional forms of P. minor are showing up. The plant pictured above was just collected and imported from China in late 2008 and appears to be another clone of, or at least very closely related to P. minor. I have small seedlings of this new form in my collection and am anxiously awaiting first flowers.
I hope that this discussion of the various forms of Petrocosmea minor is informative and helpful to enthusiasts and judges. Further study of these plants are causing me to be more and more certain that all of these plants are NOT truly P. minor. They differ from the published description in many significant ways. I feel more and more that these represent an undescribed species or "new" species to cultivation. Until this is confirmed, however, I recommend that plants be grown and labeled as we describe them here. Retaining the source of your plants is important. I try to keep records of the original labeling and source of all of my Petrocosmeas in the hopes that soon a taxonomist will provide come clarity to the labeling of these spectacular gesneriads.