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This present investigation was done in the Champasak province of Laos, and reports on the habitats of Cryptocoryne. The investigation area is located in midstream of the Mekong River. Besides the well known Cryptocoryne crispatula Engler var. crispatula two new Cryptocoryne were found and they are described here; besides these two, a number of plants interpreted as hybrids will be dealt with later, together with the general treatment of the habitats.
Description
Cryptocoryne crispatula Engler var. decus-mekongensis T. Idei, J.D. Bastmeijer & N. Jacobsen,
var. nov.
Folia lamina sensim in petiolo transiente; lamina lineari-lanceolata, 15-30 cm longa, et 0.5-1.5 cm
lata viride vel fusco marmorata, margine laevi vel crispatula. Spatha 8-10 (-12) cm longa, tubo
inferiore 1-1.5 cm longo et 0.8 cm in diametro, tubo superiore ultra 2 cm longo, in lamina patente,
ovato-lanceolata, alba et purpureo-maculata dilatato.
Type: Laos, Champasak Province, Don Khong, T. Idei no. LK 5128F, January 29th, 2009 (holotype National Herbarium of Laos, Isotypes C, E, K, L, MO).
Creeping rhizome with distinctly thickened (up to 1.5 cm thick) yearly growths, and strongly developed contractile roots. Leaves linear with a pronounced main vein, to 30 cm long and 1.5 cm broad, gradually tapering to a fine point, base narrowly attenuate, margin smooth to somewhat undulate or irregularly denticulate, green and under exposed light conditions with a brownish tinge and with brownish markings. Spathe about 8-10 (-12) cm long, kettle about 1.5 cm long and 0.8 cm in diameter, inside with a thickened wall just about the middle, lower inside wall white, upper part with alveoli (valve whitish, red streaked), red to reddish with small white blotches continuing upwards through the tube which is of about 2-3 cm in length, limb 4-7 cm long, c. 1 cm broad, linear-lanceolate, half to once spirally recurved, smooth throughout, and there is no indication of a collar (in some specimens there may be a slight indication of a collar zone) inner surface white with large, distinctly red to black purple spots. The spadix has about 6 female flowers with shortly elliptic, almost vertical stigmas, olfactory bodies rounded, purplish, male flowers about 60-90, yellow, with the surface of the thecae rough from protruding cells. Infructescence splitting in a septicidal/septifragal-ceratium-like way, greenish to purplish, globose to ovate, 11.5 cm long, smooth. Seeds brownish, 58 mm, rugose; endosperm present; embryo cone-shaped with an undifferentiated plumule. Chromosome number: 2n = 36.
Distribution
Until now only known from South region of Champasak Province, in the Mekong
River.
Etymology
C. crispatula: finely crispate/denticulate along the margin of the leaf; decusmekongensis: means the jewel of the Mekong.
Ecology. Cryptocoryne crispatula var. decus-mekongensis grows on the river banks that are
emerged during the dry season from February through April (Mekong R.C., 2010), partly in full sun. In
such places with a strong water current in the flood season it can be found sheltered between rocks
and big stones or on leeward places in the winding riverbed, and in sheltered places it can also be
found growing in sand and gravel and more or less washed mud covered. It has been found growing
together with C. crispatula var. crispatula.
Cultivation
Cryptocoryne crispatula var. decus-mekongensis grows easily in an emergent situation
in strong light and loamy sand with or without some peat litter. In prolonged emerged cultivation it
maintains its seasonal rhythm by the withering of the adult leaves and forming terete leaves from
July, with adult leaves and inflorescences emerging from November.
Description
Cryptocoryne mekongensis Takashige Idei, J.D. Bastmeijer & N. Jacobsen, sp. nov.
Folia lamina sensim in petiolo transiente, lamina lineari-lanceolata, usque ad 30 cm longa et circa
1.5 cm lata, viride vel fusco marmorata, margine crispatula, integra vel irregulariter dentata. Spatha
5-7 cm longa, tubus inferiore 1-2 cm longo et 0.5-1 cm in diametro, tubo superiore 1-2 cm longo,
lamina ante anthesin arcte tortuosa, per anthesin dilatata, erecta tortuosa, transverse valde rugosa et
verrucosa, in collo manifesto, purpureo transiente.
Type
Laos, Champasak Province, Don Khon, T. Idei no. LK 5607G, February 3rd, 2009 (holotype
National Herbarium of Laos, Isotypes C, E, K, L, MO).
Creeping rhizome with distinctly thickened (up to 1.5 cm thick) yearly growths, and strongly
developed contractile roots. Leaves linear with a pronounced main vein, to 30 cm long and 1.5 cm
broad, gradually tapering to a fine point, base narrowly attenuate, margin somewhat undulate,
smooth to irregularly denticulate, green and under exposed light conditions with a brownish tinge
and with brownish markings. Spathe about 5-7 cm long, kettle about 1-2 cm long and 0.5-1 cm in
diameter, inside with a thickened wall just about the middle, lower inside wall white, upper part
with alveoli, red to reddish with small white blotches continuing upwards through the tube which is
of about 1-2 cm in length, a 1-3 times spirally twisted limb (before anthesis), which has purple,
irregular, very pronounced transverse ridges on the surface (most pronounced on the lower part),
and there is also a pronounced purple collar structure present. The spadix has about 6 female
flowers with round, almost vertical stigmas, olfactory bodies distinctly irregular (rounded) with
protruding cells, purplish, male flowers about 80-120, yellow, with the surface of the thecae rough
from protruding cells. Infructescence splitting in a septicidal/septifragal-ceratium-like way, greenish
to purplish, globose to ovate, 11.5 cm long, smooth. Seeds brownish, 58 mm, rugose; endosperm
present; embryo cone-shaped with an undifferentiated plumule. Chromosome number: 2n = 36.
Distribution
Until now known from the Mekong River in: Laos: South region of Champasak
Province, and Cambodia: Kratie Province.
Etymology. C. mekongensis: coming from the Mekong River.
Ecology. It grows on the river banks that are emerged during the dry season from February through
April (Mekong River Commission, 2010), partly in full sun. In such places with a strong water
current in the flood season it can be found sheltered between rocks and big stones or on leeward
places in the winding riverbed, and in sheltered places it can also be found growing in sand and
gravel and more or less washed mud covered. It has been found growing together with different
varieties of C. crispatula.
Cultivation
The cultivation of Cryptocoryne mekongensis is easy in emergent situation in strong
light and loamy sand with or without some peat litter. In prolonged emergent cultivation it
maintains its seasonal rhythm by the withering of the adult leaves and forming terete leaves from
July, with adult leaves and inflorescences emerging from November. These changes are apparently
genetically fixed. This rhythm of the formation of normal long leaves and short terete (in
transaction round) leaves in Cryptocoryne crispatula var. crispatula, var. yunnanensis as well as
Cryptocoryne retrospiralis and Cryptocoryne cruddasiana is observed under unchanged emergent
cultivation in Europe (as well as other places) during the summer, when long days with more than
12 hours of daylight is prevailing (part of the time with up to 16 hours of daylight). It is so, that if
these plants during the summer time are placed under short day conditions, for example in July
under a dark tent (with black cloth and foil) with short day conditions with 11 hours of daylight,
they will produce long normal leaves (to 30 cm long) , while the other plants under long day
conditions in the same greenhouse, a meter away, will maintain their short terete leaves.
Acknowledgements
Karen Rysbjerg Munk kindly made the chromosome counts. Dr. J. Bogner kindly translated the text from English.
References:
Mekong River Commission, 2010. http://ffw.mrcmekong.org/