PS-The Hoyan

Vol. 8, #2

June,  2009


Hoya subquintuplinervis Miq. Photograph by Christine M. Burton

The yellow seen in the center is the pollinaria, which are between the inner tips of the corona lobes.

This picture was made on 25 May 2009.


Question 1: I saw your picture of Hoya subquintuplinervis on eBay and I’m sure it is the same hoya that others call Hoya pachyclada. How do you explain that? --- Too many to mention by name.


Answer:   I hate to sound like a pompous ass but, the way I explain that is, “I am right and the others are wrong.“ I spent a lot of time researching these two similar species and have a lot of documentation.  This one, which I am sure is Hoya subquintuplinervis came to me from Ted Green.  It was labeled as “Hoya pachyclada –NON-TYPICAL FORM.”*  That shows that even Mr. Green realized it was not the same as Hoya pachyclada.  I have about a 100 photomicroscopic pictures of the flowers of both species and all of their parts.  I carefully traced each part and made a chart, which shows how these two species differ. 


And now, here’s a picture of the Hoya subquintuplinervis type specimen.  Note the shape and venation of the leaves:



I also have a picture of the Hoya pachyclada type, which shows foliage as I’ve drawn it (above) but this piece is getting too long for my allotted space.  If anyone wants a copy of it, send me an e-mail and I’ll send it off to you.  Thanks go to Dr. Obchant Thaithong for providing me with these type pictures and for the drawing of the Hoya subquintuplinervis follicle..


Question 2:  But, doesn’t Hoya subquintuplinervis have flowers that are red in the center, or is it Hoya pachyclada that has the red in the center? --- The same people who asked Question #1.


Answer:  Neither of them have red in the center.  To the naked eye, the flowers of both look almost identical, but under the lens of a microscope, they are very different.  The only similar hoya with red in the center of the flower with which I am familiar is a Michael Miyoshira hybrid, which he said was a cross of Hoya pachyclada X Hoya sp. Bangkok #4.  I believe that it was actually a cross of Hoya subquintuplinervis X Hoya sp. Bangkok #4.  I say that because of the shape of the leaves and the fact that everyone, at the time Michael made that cross, thought that Hoya subquintuplinervis was Hoya pachyclada.  Here’s a picture of MM’s hybrid:


Hybrid cultivar Hoya subquintuplinervis X Hoya sp. Bangkok #4

The leaves of this hoya look exactly like those of Hoya subquintuplinervis (almost round). The red in the center of the corona was inherited from Hoya sp. Bangkok #4. The plant that produced these flowers was a gift to me from the hybridizer, Michael Miyoshira.


·         The asterisk (above) is to caution readers that this said, “non-typical,” NOT “non-tropical.”  Back in the days when I put out a Hoya Catalog and listed a Hoya pachyclada, non-typical form, I had customer after customer placing claims with me because, they said, “The non-tropical form of Hoya pachyclada you sold me froze over winter in my back yard.”  Without fail, everyone who ordered it from that catalog read “non-tropical” when the listing actually said, “Non-typical” as plain as the nose of Jimmy Durante’s face.



Question 3: I got a hoya from one of my “cutting swapping buddies” that I can’t find anything about, anywhere.

It is labeled Hoya pubifera.  Could you tell me something about this plant.  The foliage is completely glabrous so I assume the flowers must be pubescent.  Do you have a picture of the flowers? – Pat Wright, Tallahassee, FL


Answer:  Technically speaking, there is no such hoya species as Hoya pubifera.  The name means “hair bearing” but what part of the plant has hair isn’t revealed in the name.  I have been corrected by a couple of degreed taxonomists several times for referring to the holotype specimen of this and a couple of other plants because, they tell me, “Until a species has been validly published it doesn’t have a holotype.”  So, I will say, “If Elmer had validly published this species, his holotype specimen would have been Elmer’s #16971, a duplicate of which can be found in Grey Herbarium of Harvard University.  It is assumed that the intended holotype was burned by Japanese soldiers when they occupied the Bureau of Science in Manila during WW-2.  This duplicate may be the only extant example left, but it is possible that other duplicates may exist.  As a rule, Elmer distributed duplicates of his collections far and wide..

               The name pubifera is a Latin compound word.   Pubi- means “softly or weakly” pubescent (page 475-Stearns’ Botanical Latin, 4th edition).  Fera (from the Latin word “ferens”) means “bearing or carrying.”  We know that Elmer was describing the foliage of the plant because he never saw the flowers and, in fact, because of this, he couldn’t even be 100% sure that his specimen was a hoya.  How do we know this?  Because he said (in his invalid publication), “Even though I failed to secure flowers or fruits, my specimens were distributed under this new name which is here described from leaf characters only.”

Without DNA testing there is no way that anyone can, at this time, determine which plant is the same as Elmer’s #16971.  I’m not sure that Dna  can be tested on such an old, dried up specimen.  I say that because I tried to get a test on the Hoya ruscifolia type, in order to learn if it and Hoya curtisii are the same species, as I believe them to be.  I was told that such a test was impossible, due to the age and dried condition of the specimen.  That could be just a “run-around” because they didn’t want to take even a tiny piece off the specimen.  I’ve found the French very uncooperative every time I’ve contacted them with questions and requests for loans or pictures of type material.  They told me that the specimens in herbaria were not there for the purpose of helping anyone identify plant species.  I can’t think of a single other purpose of collecting and storing the specimens, but apparently others think differently.

So, without flowers, I have only Elmer’s English language description and one specimen, containing two attached leaves and two loose leaves, to rely on in determining which hoya Elmer described.   Elmer’s description follows:

Hoya pubifera Elmer,  n. sp. A crawling perennial upon a half decayed log, the older parts branched. Young stems herbaceous, slender, curved and inclined to twine, yellowish brown, soft and minutely velutinous, subterete, covered with very small papillae.  Leaves opposite, widely scattered, thick or leathery, curing grayish to yellowish brown, entire, the edges sometimes pressed with involute margins, narrowly oblong or oblanceolate to narrowly spatulate, velutinous beneath as well as densely or numerously papillose, the upper surface very similar but only slightly pubescent, the average blades 12 cm long by nearly 3 cm wide at or above the middle, the base attenuate, apex obtuse to subacute, a few of my detached leaves are only 6 cm long by 2 cm wide and with both ends obtusely rounded; midrib not conspicuous, lateral nerves none; petioles 1 to 3 cm long, dark yellowish brown, leaving circular scars upon falling.  Peduncle stout, erect or nearly so, 4 cm long, similarly papillose and of a rich yellowish brown tomentum on my specimen, terminated by a number of pedicel scars.

Type specimen number 16971,discovered by A. D. E. Elmer in woodlands at about 1500 feet altitude, Irosin (Mt. Bulusan), Province of Sorsogon, Luzon, August 1916.”   This description was followed by Elmer’s quote in the second paragraph of my answer (above).

 I believe that what you have is the same one I have.  It is IML-1301, which David Liddle sells as “Hoya aff. pubifera.  It is as bald as a baby’s butt!  The “aff.” tells you that David believes that this is something that is like Hoya pubifera, not that it is Hoya pubifera.  He also sells IML-1282 as Hoya aff. pubifera. 

I asked David about the IML-1301 as soon as I got it because it didn’t appear to be to be  pubescent like Elmer’s  plant, although its leaves were the same size and of a similar shape but they lack the involute leaf margins.  His reply to me in an e-mail dated 18 October 2006:  “It is a plant from David Cumming as “DMC5574 H. sp. pubifera” and we have just followed this convention.  It does not agree with the description of pubifera as it is glabrous and comes from Mindanao.  It is not like any of the lot we have been discussing, but it belongs there somewhere.  I have not seen the flowers so I cannot comment much more than what I have.”  Since then, he has, apparently, seen flowers as he described them in his 2009 catalog as “highly perfumed small purple flowers.”

               When I get a cutting from David Liddle (or anyone else), if it is long enough, I cut it up into 2 node cuttings.  I root all of them.  Then I sell one on eBay and keep the rest for myself.  This is how I earn the money to buy more (and sometimes to feed my face).  I’m holding on to all my cuttings of IML-1301 until I can see what it’s going to do next. When I got it, the cutting was long enough for four cuttings.  I put three of them in a 6” basket, where I expect them to stay for several years.  The other one, I put in a 3” inch Solo cup (with a hole in the bottom) and planned to sell it on eBay.  What I didn’t expect was that it would grow in an unusual way.  Most hoyas (all I’ve seen until now), once rooted, will put out a single long shoot from a leaf axil.  This one hasn’t put out a single shoot but from that leaf axil there must be at least twenty-five to thirty leaves.  All look healthy but I see no sign of a stem or any nodes.  Those leaves are still only about an inch long.  I’ll be watching this carefully as I’ve never seen a hoya grow like that.


Question 4:  Do you have a picture of Hoya hellwigiana?  What does it look like? --------- The same who asked about  the above.


Answer:  No, I don’t have a picture.  I do have a picture of the one listed in David Liddle’s 2009 catalog as IML-1101 hellwigiana, but I think that the label on my plant mist have gotten mixed up with the label on another species, because there’s no way that the hoya I have with that label on it could be Hoya hellwigiana.  The reason I say that is because the plant I have so labeled has very conspicuous veins in the tri-nerved, tripli-nerved pattern.  Here is how Warburg described the leaf veins of Hoya hellwigiana: “venis utrinque ca. 2 ascendentibus fere omnino inconspicuis.”  That translates into “veins, about 2 ascending, almost entirely inconspicuous.”