Friday, January 25, 2008

Hydnophytum - Part 6

A picture is worth more than a thousand words: the leaves of various Hydrophytum sp. in the formicarum - moselayanum complex placed side-by-side. Noticeably, the lateral veins are more prominent in the formicarum and leaf thickness increases towards moselayanum.

Trying to justify back-dating this posting; this jpeg composite was created way back in mid-Jan 2008.

Sunday, January 13, 2008

Hydnophytum - Part 5 (moseleyanum)

This is a composite picture. Click and open in new window for an enlarge version.

Clockwise from the top: (1) Commonly traded species in US (2) Sp from Papua, ex Botanical Gdn, Europe (3) Sp from Northern Australia ex Botanical Gdn (4) 2 Sp from Triton Bay, Irian Jaya.

The commonly traded species has been identified as H. moseleyanum (syn. H. papuanum) and is also almost identical to the species from a Botanical Gardens in Europe collected in 1960s or 1970s from New Guinea. They have matt lime-green semi-succulent leaves and silvery brown tubers. The species from Northern Australia is also similar but is more deciduous under the same cultivation regime. It shreds leaves easily when dry. Finally, 2 species from Irian Jaya looks more intermediate just like the other H. aff. moseleyanum from the Philippines and Bogor, Java. These 2 irian plants differs in having longer pointed leaves.

Maybe it is more practical to define this group as a formicarum-moseleyanum complex rather than to pin a name to it.

Saturday, January 12, 2008

Hydnophytum - Part 4 (aff. moseleyanum)

I started off by introducing Hydnophytum with affinities to H. moseleyanum without introducing H. moseleyanum. Why? The reason will be obvious in part 5. Here, i have taken the liberty to label those which have the H. moseleyanum look but are found outside and farway from New Guinea.

The above species comes from the Philippines. Like the former Bogor plant, it has semi-succulent leaves stacked closely together and the veins are not prominent.

Thursday, January 10, 2008

Hydnophytum - Part 3 (aff. moseleyanum)

You may now notice a trend of featuring Hydnophytum from west to east. I am trying to show the variation of Hydnophytum species complex; some may be distinctive enough to be a species on its own while others are just too fluid and form a continuous change from formicarum to moseleyanum from Sumatra to New Guinea.
This one comes from Bogor, Java. However, i'm hesitant to say that it is from Java because it actually comes from Bogor Botanical Gardens. What's the chances of picking up dropped clump of hydnophytum seedlings during a garden stroll? This is probably the most interesting species amongst hydnophytum with great horticultural potential. The leaves are relatively small, shiny and a bit succulent. The branches are short and would form branchlets. The caudex is also very smooth, silvery green and shiny. And for the best part, the caudex grows faster compared to say H. formicarum and even H. moseleyanum. It is relatively tolerant of low humidity and burst into caudex growth when it is given generous watering. Well it definitely has more affinities to H. moseleyanum.

Tuesday, January 08, 2008

Hydnophytum - Part 2 (aff. formicarum)

Continuing from Part 1, this species comes from the island of Borneo. It is really similar to H. formicarum in Part 1, except for the generally smaller stature and having linear leaves. It is definitely a slower plant compared to H. formicarum type and it has to start off life with a smaller seed too.

Sunday, January 06, 2008

Hydnophytum - Part 1 (formicarum)

I wonder if anyone has heard of antplants? Okay, there will always be ants around plants looking out for food - coaxing sugary secretions from mealies, feeding on nectar rich flowers, collecting sweet secretion from nectary glands on leaves giving some protection to Impatiens. More specifically, i shall refer to antplants as plants that provide a home for the ants. The family Rubiaceae has a few highly evolved genus - Hydnophytum, Myrmecodia, Myrmephytum Anthorrhiza, Squamellaria which provide a complex honeycomb structure for housing ants! These plants have a fat stem base or "caudex" that can house ants, and in nature antplants are invariably populated with ant colony. In cultivation, these plants also develop a caudex irrespective of whether ants choose to migrate or live there. There is a symbiotic relationship between plant and ants. Ants provide nutrients and at the same time protect antplants from its insects or even human enemies. While the antplant provides a shelter for ant colony. Well, i don't want to go into the details but Nick Plummer has a good website that covers this topic with a reference list.

Hydnophytum is the genus with the widest distribution from Fuji Islands in the Pacific to Andaman Islands in the Indian ocean and from Southern Indochina to Cape York in Australia.
Let's start off with the better known Hydnophytum formicarum (photo above). This plant is in cultivation in both private and botanical collections for sometime. Various distinctive forms or varieties are available from specialist nurseries time to time and they are mostly labelled as H. formicarum. Personally, these are probably variations of one species complex or have evolved into different species from west to east. Base on regional flora, Hydnophytum represented by one species which is H. formicarum in Andaman Islands, Peninsular Thailand & Malaysia, Sumatra. Observations of wild H. formicarum plants in Peninsular Malaysia and its offshore islets in the South China seas yield little variation. Thai plants are also similar. The leaves are leathery and have prominent veins, tubers are invariably dark brown with ant entrance holes irregularly placed. The "spination" or "bristles " covering the tubers are root stubs which stop growing. Tuber ridges and lobings are irregular. Having seen many seedlings from the same mother plant, the caudex is shaped more by environment conditions then genetics. More to come... in Part 2.

Saturday, January 05, 2008

A Tuberous Impatiens

This is probably one of the better known impatiens amongst caudiciform and succulent growers, little known in the wider ornamental plant growing community. Werner Rauh has chosen this species to be included in his book Succulent and Xerophytic Plants of Madagascar Volume One, Strawberry Press (1995). It is aptly named Impatiens tuberosa. It is a perennial which sheds its stems during the dry season when it goes dormant. With the onset of the next growing season, new stems will emerge from the dormant buds on the stubby irregular above ground tuber. The plant comes from Montagnes des Francais near Antsiranana and Windsor Castle in Northern Madagascar on limestone cliff. It is likely to be found growing in cracks with accumulated peat with other Euphorbia species from the same area.

The flowering plant above is only 3 mths old from seed! Perhaps its rapid growth is an adaption to the strongly seasonal climate with a short rainy monsoon. The caudice is not obvious at this stage. But it is clear from the photo below that the stem will abscise just above the tiny bud: