HOYA AUSTRALIS- a brief history

PROLOGUE- This history will appear in five chapters, History, Taxonomy, Distribution, Trivia, and Variations. Please don't post on this thread until after Variations has appeared, then start posting!
A few notes: this is for everyone of all levels of knowledge and cultivation skills. There are no dumb questions, so ask if you can't figure something out through the article or diagram. If this information appears elsewhere or is critiqued, that's fine by me. In this forum, it's just for us. This is a slightly simplified version of this article. The full article is available to all DG'ers. Just DGmail me your regular e-mail address and I will send it to you. This photo is my own australis ssp. australis celebrating this article, and was taken minutes ago

HISTORY- Hoya australis was first collected by europeans in 1770, by Banks and Solander, two of the scientists aboard James Cook's ship HMS Endevour, on his first voyage of discovery to the Pacific. The plant material was collected from Cape Grafton near Cairns, Queensland, on the northeastern coast of Australia. The Pacific Island form of the plant was next collected from Tanna by Georg Forster, the Botanical Collector and Draftsman on Cook's second voyage of discovery. Forster assigned it the name Ascelpias volubilis, a name associated with a number of other species, as Taxonomy was in its formative stage.
In 1810 Robert Brown created the genus Hoya. He moved two descriptions from the Genus Ascelepias (Linnaeus) into this new Genus. Hoya carnosa (including the australis material), as the Holotype for the Genus, and Hoya viridiflora. The name Hoya australis was published in 1827, by James Traill, based on the Australian collection of Banks and Solander. Subsequent authors named plants from a number of areas in Australia, and Papuasia which were later combined within Hoya australis by David Liddle and Paul Forster in the 90's. They ultimately published/ republished the complex as five separate sub-species.
The australis complex has spread throughout the world in cultivation, giving rise to numerous cultivars, varieties, and hybrids (as well as many confusing and arbitrary designations). It is now one of the most popular and common species in cultivation, third only perhaps to the Hoya carnosa complex and H. bella.
Recently australis ssp. oramicola has been classified as a "vulnerable" species by the IUCN (international Union for the Conservation of Nature). Also mentioned as of "least concern" (a less endangered species) is ssp. rupicola.
More recently Hoya australis has begun to naturalize in Hawaii. Carol Noel recently found a seedling she has identified as australis ssp. australis growing near the beach which she has collected and introduced to the trade.

TAXONOMY- Hoya australis is in the Hoya section pterostelma. Other members of this section are H. calycina, H. naumanii, H. albiflora, H. magnifica, and BSI-1 (syn. subcalva). H. albiflora and H. magnifica are often misidentified in cultivation. The specific epithet "australis" refers to the latin term for 'southern', not specifically to Australia.

Here are some brief descriptions of typical plants of the 5 subspecies:

ssp.tenuipies- this ssp. is always glabrous (leaves and stems hairless). The umbel (flower cluster) is loose and has clear white, starry flowers. The flowers are smaller and the pedicels thinner than ssp. australis. It comes from a moister environment than the other ssp. Flowers heaviest September to October in Australia, spring in the northern hemisphere.

ssp.australis- can be glabrous or pubescent (leaves covered with fine hair), the umbel is a tight collection of flowers that can be relatively small or large. Most specimens in cultivation are probably of this ssp. It is very variable, with many different leaf forms. Flowers heaviest March to May in Australia, fall/winter in the northern hemisphere.

ssp. sanae- pubescence varies but always pubescent. this ssp. is more xerophytic than the two above, but still viney. It has small quilted leaves that have recurved edges. Flowers May to July in Australia. It occurs on sand near the beach in Australia.

ssp.oramicola- Mostly glabrous with medium size rather succulent flowers, has bright green, more succulent leaves than sanae. It twines, and is not bush-like, it has thick quilted leaves. Flowers January to March in Australia where it occurs on red laterite soils

ssp. rupicola- Densly pubescent to glabrous, very succulent leaves, leaf edges not strongly recurved as in ssp. oramicola or ssp. sanae, is very xerophytic, and could be classified as a true succulent. The leaves are very thick and smooth, with no quilting. This subspecies along with ssp. oramicola has a slightly different floral structure than the first three, with short corolla lobes and calyx lobes visible from above between the sinuses. Flowers January to March in Australia where it occurs on sandstone.

I must thank David Liddle, who was kind enough to answer many of my questions involving the history, taxonomy, and distribution of Hoys australis. He also provided the photo montage which accompanies this post.

DISTRIBUTION- All ssp. of australis are found naturally occuring on the Australian continent. In addition, ssp. australis and ssp. tenuipes are also found naturally occuring in Melanesia and Papuasia. They have many forms, especially ssp. australis, and this with it's wider distribution has led to many of it's misnomers.
Hoya australis probably has several pollinators in habitat. One well documented one is Ocybadistes walkeri, usually grouped with butterflies although it is moth-like, and is diurnal. Birds pollinate clones of australis in David Liddle's Australian nursery, and in cultivation elsewhere it has been bee-pollinated. It's white flowers and heavy scent suggest that it may have a nocturnal pollinator, although these traits may have evolved to attract dawn or dusk-active species.
The map which accompanies this post is a public-domain image.

TRIVIA- Hoya australis can be toxic to cattle and certain other livestock if consumed in large quantities. According to Dr. Ross McKenzie in his 1993 paper "Australian Native Poisonous Plants", "(Hoya australis) growing in the softwood scrubs of Queensland has been used as drought fodder for cattle. To much will damage spinal function and the cattle will collapse and may die". I have found no reports of toxicity to humans or household pets.
There are many traditional remedies involving Hoya australis used by Pacific Islanders. In Fiji it is (was) used to treat swollen testicles and hemorrhoids. In Tonga and Samoa it was used to combat inflammation and convulsions.
Hoya australis uses a procedure known as Crassulacean Acid Metabolism (or CAM). In this process the plant closes its stomata (pores) during the day to reduce the water loss which occurs during transpiration. It opens its stomata at night to take in CO2 and release oxygen. Note- this dosen't mean that australis should be watered at night- it will take in water when it is available, and breathe on it's own schedule. The diagram is my own.

VARIATIONS- There are many varieties of ssp. australis and ssp. tenuipies. Here are some of the most well known:

cv."Brookfield"- is a variety of ssp. australis with bronze new growth and larger flowers. It is sold by David Liddle from his Australian nursery.
cv."Mrs.G"- is distributed in America by a few dealers. It was published by Carol Noell, and is said by her to have a more compact and floriferous habit. A clone of ssp. australis.
cv."Lisa"- is a lovely variagated form with shades of pink, yellow, and several greens in complex patterns. New growth is often tinged purple. A sport of ssp. australis.
cv."variegata"- there are at least two variegated clones of ssp. australis, perhaps more.
ssp. australis from Kapoho- with huge leaves and good flowering habit is sold by Aloha Hoya.

There are many natural variations of ssp. australis. Leaf shades range from very dark green to pale olive to shades of yellow-green. Leaves may be small (1" x 1") large (up to 9" x 6") and may be glabrous or covered with fine hairs. Flowers vary somewhat less, ranging in size from 1/2" to nearly 1", and almost always being white with a stain of carmine under the corona (the carmine color is usually reduced on ssp. tenuipies). Some clones display more carmine markings on the corolla petals, a very few show a degree of pink blush on the corolla.
There is a hybrid of australis and BSI-1(syn. subcalva) produced by Ed Gilding. To my knowledge, he distributed seedlings of this cross to a number of sources. One offered by Aloha Hoyas is pictured in this post. Another clone is offered by Ted Green, this one is named Hoya X "pinkie". There have been speculations made by several experts that Hoya naumanii may be a naturally occuring hybrid of australis and BSI-1. It was collected around 1980 on gizo, near Bouganville. Australis and BSI-1 occur in the immediate region.
Availability of plants: Most subspecies are available through David Liddle at his australian nursery and Ted Green of Hawaii. Carol Noell of AlohaHoya (also in Hawaii) has several interesting forms of australis and may have other ssp. available in the future.
This photo is my own BSI-1 x australis, received from AlohaHoya.

Mark Randal,
with technical assistance from David Liddle

A few notes:

Melanesia is a group of islands near Australia including New Guinea, the Bismark and Solomon Islands, New Caledonia, Vanuatu, and Fiji.

Papuasia is a botanical region consisiting of New Guniea, the Bismark archipelego, the Solomon Islands, Bouganville, and the Aru islands.

Many botanical terms are defined in the Dave's garden information files.

Once again, I have to thank David Liddle, who provided invaluable information on many aspects of this plant group. Carol Noell provided much information, feedback, and encouragement. Thank you both!

Mark Randal

WOW, that's great information. I will print it off so that I can study it and have it as a reference.

Thank you Mark

Linda, the DG format dosen't lend itself well to saving- if you want to send me your e-mail through DGmail, I'll send you the whole article with the floral diagram.
and you're welcome!

That would be wonderful, thank you so much

lhughes2@sc.rr.com

Mark - what a work of love!! SO informative, easy to read and understand, full of information...really really GREAT. Now...who in their right minds could do a better job than you have!!!...it has certainly set the standard for what we need to do with other hoyas!!

Personally, I would love a copy of your Report with photos. A REAL keeper!

Hats off to you -

Aloha, Carol

I am with Carol......Great job...I would also love a copy with pics. SANDYC

Awesome Mark!!! Thank you!
Ann

Carol has started a seperate post for discussion of our growing experiences with australis, so check that out as well!

This message was edited Dec 18, 2005 12:10 AM

Excellent work. Thanks Mark!

Thanks, Mark - as a newbie this is invaluable!! I appreciate all the work you put into this - I'm going to print it out! This whole "hoya of the month" idea is fantastic - a great way for this newbie to learn!! Thanks - Karen

I got my article, thank you Mark for a very informative study.

(now I've got to find me a cutting)

Mark, thank you so much! That must have taken some time! Very informative. This post will definitely go into my hoya folder!!
Heather

I am soooo glad you did this Mark. Thanks from me too. This has been very interesting to read about. I would LOVE to have the article sent to my email also so I can save it. Please send to:
Walkzwdogs@aol.com
Thanks again!
Marcy

Here is a hyperlink to AlohaHoya, check the catalog for ssp. australis varieties:

http://www.bigislandgrowers.com/ghp/AH.php

And here is Ted Greens website, usually a good variety of ssp.'s:

http://www.rare-hoyas.com



This message was edited Dec 18, 2005 6:21 PM

Zo....Mark. A question....sort of OT. Aside from learning about H. australis...were there any other lessons re: hoyas you learned in this exercise?

Carol

Definitely- the biggest one was how difficult research can be when you're dealing with plants that are not extremely popular in cultivation. If you were to explore, say, marijuana or poinsettias, you could just go on line and find more than enough information about them for a hundred articles. With Hoyas (and other plants I have grown, euphorbias or salvias say) you get discussion groups like this one which hopefully will have more experienced members, and are a good source of info. My botanical library (a good one at Strybing Arboretum in Golden Gate Park) has some source material, namely the bound copies of The Hoyan and some of Kloppenburgs work, but is by no means a comprehensive source. Luckily, meeting David Liddle made all of the difference, as he has researched these plants thoroughly over the years, and lives in their native region.
It is still a bit of a suprise that you can put the name "hoya carnosa" in a websearch and after filtering get two or three sources of real information, while entering the name "Paris Hilton" will give you more data then you could process in a lifetime. Human priorities, hmmmn...

Wonderful, well written information!

Blessings,
Awanda

Mark,
Very interesting. Thank you so much for your time preparing this for us. I would like to have this article as well.

wtfrank@peoplepc.com

Thanks again, wonderful job
Tami

Mark - I'd like the article, too - email is bobkaren@wireless111.com. Again, thanks for all your hard work and willingness to email this to us. Karen

I'd love to have it as well...
zonaldenial@yahoo.ca

Thank you Mark! Ü

Yes, Mark. It is very interesting the kinds of information available on the "information superhighway." It is too bad that the internet seems to be turning away from what ostensibly could be a resource that "levels the playing field," when it comes to information, to something for shopping and celebrity scandal - it is disheartening. Just to give a funny example, my cat had a stroke two years ago and when I turned to the internet to see what I could find about "feline stroke", well you can well imagine what the first several hundred google links were to.... It's gotten better since then, thankfully.
I really like this forum because I can at least turn to you folks for information about Hoyas.
Ann

Mark, thanks so much for putting this great thread together! Awesome job!
Me too, please.....sjmccarty@houston.rr.com.

I say we have "Hoya of the Month" from now on. I will pick one and start researching too, but it's going to take a while!

Great Susan, tell us when you pick one, so we can start anticipating! How about when you post yours, someone else can volunteer on your thread for the next one....

Ann, Amen to that. Taxonomy is half the battle, you want to make sure you know whats what so you can make your shopping lists. But I'm glad to leave the debate to the experts, I just want to grow and smell them. Thats where other amateur growers come in, since they will be growing plants in conditions similar to mine- i.e. not optimal, inside, near vents, around cats, you name it. the professionals have greenhouses (not fair) or live in Hawaii (double not fair).

I agree with the "double not fair" of the plant growth in Hawaii. Carol has eriostemma's growing with wild abandon on trees. The vines go so high up the tree you have to cock your head back and shade your eyes to try to see it all.
Ted Green threw cuttings of H. affinis fraterna over his garden fence and it is covering the trees on the "wild side" of the other property. I think about this every day and just shake my head. Ted Green is a very cool guy! I could have hung out with him forever.

It's going to take me awhile to work on a hoya of the month. With a merger at work and three co-dependant males at home, plus 4 cats and two dogs I have minimal free time.

I also have an unknown H. austrailis I need to photo and post here.

I forgot to post my email, hbabcock@mn.rr.com. I would love a copy of the article.
Heather

Mark,
Thank you for posting all the great information on Hoya Australis. I would love a copy of the article. I am sending my email address with Dmail.
Thanks,
Patti

Just read thru this again, Mark. Really a great job!!!!

Carol

I have only a couple of Hoyas and am a newbie to them really. You are right, there is more about Paris Hilton on the web than Hoyas.. lol.

Thanks for posting this info it has been a tremendous help. Also the photos you posted really helped me to ID an pendicule.. (sp).

Antoinette

Gorgeous plant..........I really hope that one of mine *will* be correctly named and bloom to look like yours Mark!

Mark...

The same H. australis that bloomed in the fall (H. australis ssp. australis) is blooming now (H. australis ssp. tenuipes). Does this mean I'm nuts? LOL.

Carol

I don't know for sure... I think in the generous conditions of cultivation maybe australis (and other Hoyas) are more inclined to bloom for a longer period of time than in their natural environment? At least, those from harsh environmental conditions, where water/nutrients are limited. I suspect that in cultivation ssp. australis will bloom sporadicaly throught the year if conditions are to it's liking.
Ssp.australis and ssp. tenuipies seem to be easier to confuse than other ssp.s, which have more distinctly diferent leaves. Ssp. australis has been said to always have some pubescens to the leaves, but I have a clone with completely glabrous (hairless and smooth) leaves. I don't think you can tell for sure by the leaves alone between these ssp.'s. One good indicator may be that ssp. australis has a slightly more campanulate flower, especially when it is opening up (see the first picture on this post). Ssp. tenuipies has a finer flower with narrower corolla lobes (petals), and usually less red under the corona. I also suspect that while ssp.australis can bloom throught the year, ssp. tenuipies will be more inclined to bloom only in spring, as it is said to be a stingy bloomer.
There is some question to the identity of these ssp.s. David Liddle and Paul Forster, who wrote the book (so to speak) on this group of plants have ssp. australis as the campanulate flowered heavier bloomer, with larger clusters of flowers and mostly pubescent leaves, and ssp. tenuipies as the finer flowered, narrower pediceled stingier bloomer, with mostly glabrous leaves.
Chrstine Burton seems to feel that the ssp. names are the reverse, as you can see on her website P.S. the Hoyan.
I'm going with the Forster/Liddle version, as they actually did the field work and wrote the descriptions of these plants in their paper, Variation in Hoya Australis R. BR. ex Traill.
Don't take me as an expert on I.D., I have grown and flowered ssp. australis, and have a small ssp. tenuipies from D. Liddle himself. One the ssp. tenuipies is larger and has flowered, I should have a better take on these plants.
One thing that points towards ssp. australis as your plant is that David has mentioned a large leaved pacific island form of ssp. australis, which may agree with your plant, since it is large leaved and does come from a pacific island!