PS-The Hoyan

Vol. 6, #3

July, 2007


            This issue will be devoted to a few species featured in the publication, Phylogenetic Relationships Between Hoyan and the Monotypic Genera Madangia, Absolmsia and Micholitzia by Livia Wanntorp and Paul I Forster, in Annales, Missouri Botanical Garden  94: 36-55 (2007).

            Somehow, I can’t believe that Dr. Forster had much of anything to do with this publication, which I believe to be very poorly researched.  I have no degrees in taxonomy but I found errors that anyone who had even read the original name publications would have avoided.


1). This publication “sunk” Micholitzia obcordata N. E. Br. into synonymy with Hoya yuenanensis Hand.- Mazz.

This sinking can be found on page 45 of the cited publication.  The synonymy cited is, as follows: Hoya yuennanensis Hand.-Mazz (author says “Holotype not seen”);

Micholitzia obcordata N. E. Br. (author says “Holotype not seen”);

Hoya lantsangensis Tsiang & P. t. Li (author says “Holotype not seen”):

Hoya manipurensis Deb (author says “Holotype not seen”).

I hear echoes of R. Rintz, who also did a lot of sinking without having seen any of the type specimens he sunk.

I have seen the type specimen Hoya lantsangensis Tsiang & P. T. Li though I wouldn’t need to see it because the authors illustrated it so well when they published it.  Likewise, Deb illustrated his publication of the name Hoya manipurensis.   I have not seen a holotype of Hoya yuennanensis  Hand.-Mazz. but I do have a copy of the original publication which can be found in Symbolae Sinicae vol. 7, page 1001.  This was published in 1936. No one who has read Handel-Mazzetti’s description could ever confuse Micholitzia obcordata with Hoya yuennanensis.


Here is how Handel-Mazzetti described Hoya yuennanensis: 

Leaves 6 to 10 cm. long  by about 3 to 5 cm. wide; shortly & obtusely apiculate; bases broadly rounded or truncate, very thick, flat, both sides crisply hirsute, in juvenile state almost villosa beneath, nerves, 5 to 7 pairs, at about 60º, straightening and joining before reaching margins.  Flowers noted on living plant as pink, outside glabrous, inside shortly velvety.  The description is long and has a lot of detail that is often missing in hoya descriptions. The last paragraph is very revealing.  The author says that it resembles Hoya carnosa, which is more glabrous and Hoya lyi. He also says that its flowers are only a little different than those of Hoya villosa.


This is a sketch of a Hoya yuennanensis leaf, as described by Handel-Mazetti, author of this species.  In sketching it, I assumed that the author’s definitions of leaf shapes were the same as those defined in Stearn’s Botanical Latin.  Not all are so this may not be exact. I’m sure it is close.

I may be wrong but I believe that this is the species Costantin illustrated (wrongly), as Hoya carnosa, in .Flore Generale de l’Indo-Chine (1912).




Hoya lantsangensis Tsiang & P. T. Li.





            I do not believe that Micholitzia obcordata is a hoya but, if it is, then the correct name for it should be (assuming we must choose between those cited by Ms. Wanntorp) Hoya manipurensis  Deb, because its publication (1955) preceded that of Hoya lantsangensis Tsiang & P. T. Li (1974) and because the name Hoya obcordata is already occupied, having been published by J. D. Hooker in 1883.


Other Things in Same Publication


1). Page 53.  Here you’ll find the statement that “Forster et al. (1997), who mentioned Hoya heuschkeliana as the only species with similar corolla shape. Omlor (1996) also mentioned a  species from Sabah, H. telosmoides, with a similar corolla shape, etc.”  The fact is that Hoya vacciniiflora Schwartz (1931) from Western Borneo has a corolla almost identical to that of Hoya heuschkeliana (just a little more open at the top) and it’s corona looks more like a true hoya corona than any of those mentioned.  Hoya telosmoides looks little like any of them as it has long corolla lobes (only the undivided part is round).


2). On page 49, the author (without having seen types of either species and without, apparently, having read either publication) has placed Hoya retusa Warb. into synonymy with Hoya retusa Dalz.  This is not correct.  Hoya retusa Warb. is a large plant with leaves that measure about the same (or slightly larger) than those of Hoya kerrii.  They are retuse at their outer tips.  This species has been given a new name by P. T. Li, of Hoya tsiangiana P. T. Li. All of the pictures of Hoya retusa Dalz. on page 51 match those of mine except the corona profile.  It is different from pictures of flowers of the living plant and also different from those of topotype specimens George Slusser photographed and that I sketched from flowers of same plant and herbarium specimen..


3). The author featured a hoya she labeled as Hoya venusta Schltr. again saying holotype, not seen.   I have seen the holotype.  I am 100% certain that the hoya pictured on page 52 of this publication is not Hoya venusta.  It is, without a doubt, Hoya microphylla Schltr.


4). The hoya pictured on page 41 is the hoya being distributed as Hoya caudata from Sumatra.  It is not, in my opinion, Hoya caudata.  I have been working on a Latin diagnosis and will be presenting it for publication, shortly.  It differs from Hoya caudata in the outer tips of its corona lobes being very broad and almost truncate.  It also differs in that its leaves are hairy.  The hairs are short and hard to see but feel rather stiff and bristly.  The stems are also covered with these stiff bristly hairs.  These hairs are easy to see on the stems.  This one is a lot easier to grow than Hoya caudata is.  I don’t know what the pollinarium on page 41 is.  It looks like none other I ever saw.