by Jan D. Bastmeijer ~ 2016
Suwidji Wongso & Co.
These pages are on the cultivation and taxonomy of plants of the genus Cryptocoryne & Lagenandra (Araceae)
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Cryptocoryne siamensis Gagnep. var. siamensis

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Cryptocoryne siamensis var. siamensis originates from the limestone in peninsula Thailand, what means that the water is not as acid as for the other members of the cordata-group. It became from the 60s a very popular aquarium plant under the name "Cryptocoryne blassii" because of its broad, brown leaves with a wine red lower side. From the 80s, Jacobsen made many trips in that area and found a lot of variation in leaf form and colour, as for the limb of the spathe. See the Synonyms page for changes in the names. There is a lot of variation in color and shape of the leaves, each stream has 'his own' siamensis.

Click on the picture to get the full image (ca. 50 kB)

A small stream on peninsular Thailand with on the sheltered side stands of C. cordata var. siamensis.
coll. NJT 03-01
photo Jacobsen
A close up of this patch. The leaves are coffee brown on the upper side.
coll. NJT 03-01
photo Jacobsen
The same stream with plants which are more greenish.
coll. NJT 03-01
photo Jacobsen
Again the same stream. The limb of the spathe varies from bright yellow to brownish.
coll. NJT 03-01
photo Jacobsen

Another part of the stream in peninsular Thailand. You see the wine red lower sides of the leaves.
coll. CC 204-1
photo Christensen

There are very many streams in peninsular Thailand with C. siamensis var. siamensis. All slight different.
coll. NJT 04-31
photo Jacobsen
C. siamensis var. siamensis also grows in this very deep spring.
coll. NJT 02-15
photo Jacobsen

Fresh collected plants.
coll. NJT 02-15
photo Jacobsen

An aquarium picture of C. siamensis var. siamensis. The plant is best grown in hard water..
coll. unknown
photo Möhlmann

In shallow water, the brown leaves reaches the surface. The spathe grows out of the water, making pollinating possible by small flies, which might be attracted by the odour of the inflorescence. Note the slight bullate leaves.
coll. unknown, cult. Bot. G. Copenhagen P1671-9
photo Jacobsen
The 'classical' C. siamensis var. siamensis ("blassii") has a more or less developed brown tinge over the limb, most prominent on the edges. The (bullated) leaves are broad cordate to ovate and can be quite brown and have a deep purple red lower side.
coll. unknown, cult. B 17
The leaves of this plant are very dark with fine purple dots on it. The lower side deep purple. The limb is brownish at the edges. Note the somewhat swollen throat, called a collar zone.
coll. unknown, cult. B 290
The limb is quite glossy. The leaves are ovate and have a brownish upper side and a deep purple lower side of the leaves.
coll. unknown, cult. B 16
A more reddish limb of the spathe Note also the much more swollen collar zone.
coll. & cult. NJT03-1B
photo Jacobsen
Tomey collected this plant in the north of W. Malaysia. It is not certain if we must attribute it to C. siamensis var. siamensis.
coll. Tomey s.n., cult B 295
This plant has big cordate leaves without any purple, the upper side dark green, the lower side is pale green. The chromosome number is however 2n = 85.
coll. unknown, cult. B 18
A quite red limb of the spathe. Note that there are small red (or brown) dots, the size making the difference.
coll. & cult. NJT02-15
photo Jacobsen

Opened kettle showing the spadix with the female flowers (bottom) and the male flowers (above). Note the purplish appendix on top ands the white kettle wall inside.
coll. NJT02-5A, cult. B 868
Compared to the picture left, note the dark styles of the female flowers and the red colour of the lower part of the kettle.
coll. NJT02-14, cult B 881
A longitudinal section through the female flowers showing the bright yellow olfactory bodies.
coll. unknown, cult. B16
Isotype of C. siamensis var. siamensis collected in peninsular Thailand.
coll. Kerr 17094
Nationaal Herbarium Leiden
Drawing of the holotype (Kew herbarium) in de Wit 1990.
coll. Kerr 17094
drawing Ike Zewald
Drawing of the type specimen of "C. blassii"   also in de Wit 1990. The short naked axis between the male and the female flowers is not typical.
coll. unknown, cult. Blass
drawing Ike Zewald
Distribution of C. siamensis var. siamensis on the peninsular Thailand and - probably - the very north of West Malaysia.

Cultivation is quite easy in water with hardness up to 25 DH. The plants easily reach up to 20 - 30 cm, making them much wanted by aquarists.
Brian Seccombe (AUS) made a time lapse photo series of the opening of the limb, see his movie.

See the cultivar C. siamensis var. siamensis 'Rosanervig'.
See also the other Cryptocoryne of the cordata-group.

Literature: see the cordata-group.

Updated January 2016

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