Habitats

During a stay in Thailand in February 1977, I had the opportunity to study different Cryptocoryne populations. Three localities will be considered:

1. Mueak Lek (Fig. 11), c. 150 km NNE of Bangkok. Alt. c. 200 m. The 6-8 m wide river runs through the park near the main road. The water was rather calcareous and had a temperature of 24 C. Calcium carbonate incrustations covered almost everything that was under water, and in places with some water turbulence the result was formation of magnificent travertine dams across the river, creating small waterfalls. In the pools thus formed, a rich, submerged growth of Cryptocoryne crispatula was found (NJ 77-16). The largest plants were 50-70 cm long, with bullate, 30-50 cm long and 2-4 cm wide leaf blades (Figs. 12, 26). The leaves, except the youngest, were incrusted with a layer of calcium carbonate (these large-leaved plants represent what in the past has been named C. balansae).

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Fig. 11. Mueak Lek. Habitat of the broad-leaved, submerged form of C. crispatula var. balansae

Fig. 12. Mueak Lek. Submerged plants of the broad-leaved form of C. crispatula var. balansae

Fig. 26 (lower right). Uprooted plants of C. crispatula var. balansae from Mueak Lek: Left a submerse plant, right an emersed plant

Flowering specimens were found in places where the bottom of the river was raised to the surface of the water (leaves 20-40 cm, spathes 20-30 cm), and also on the banks at the top of the dams, where the leaves and the spathes were 10-15 cm long (Figs. 7 J, 31). The limb of the spathe of these plants was grayish grounded and had long purple markings.

2. Phu Khieo Wildlife Sanctuary, c. 350 km NNE of Bangkok. Alt. c. 700 m. The river, Huae Mae Chem, is 8-10 m broad, mostly filled with rather large, round stones and rocks (Fig. 13). The river is running quite rapidly and is less than 0.5 m deep during the dry season. The temperature in the water was 21 C. The Cryptocoryne were growing on the banks of the river in large quantities. The leaves were 10-20 cm long, 0.6-0.8 cm wide, green and smooth (Figs. 7 F - G, 16 B). In sheltered places they formed large carpets. Most of the plants were emerged and even though most of them had flowered a month or two earlier, a few could still be found in flower. Plants from this main course of the river formed the basis for the description of C. bertelihansenii, which is now recognized as a synonym of C. crispatula var. crispatula.

In a quiet, shaded tributary, just east of the main course, plants with a different foliage were found. The leaf-blades were almost copper-brown, bullate, 20-30 cm long, and 1-2 cm wide (Figs. 7 H, 16A). The limb of the spathe was yellowish with short, purple lines (Figs. 10 E, 39, 40). Some plants with foliage intermediate between the brown and green-leaved forms were found only a few meters from the brown-leaved plants. In these intermediate plants the limb of the spathe was grayish with longer, irregular purple lines, resembling those in the main course of the river.

On the west bank of the main course of the river was another small, shaded tributary, almost carved into the solid rock (Fig. 17). Here was a pool (4 × 15 m) with a depth of 0.2-0.5 m. The temperature of the water was 16° C. In cracks in the bottom of the pool plants with brown leaves were found, similar to those from the other tributary (both representing C. crispatula var. balansae). Just above the pool, in full sun, green-leaved forms grew abundantly between the rocks.

Material representing the different leaf-forms found at Phu Khieo (Fig.18) has been grown and flowered under identical growing conditions in Copenhagen. The leaf-forms are for the most part maintained constant under these cultivation conditions. All collections at Phu Khieo were made within 30 meters of each other and they are all regarded as representing C. crispatula.

3. In the Thai part of the Malay peninsula, south of Ranong, several localities with C. albida were visited, but the population at Ban Nang Yon (Note: Misspelled: Ban Wangyon, 1991), c. 100 km S of Ranong (Figs. 1, 22, 23, 24) is quite representative of the situation on the whole. Alt. c. 10 m. The river is about 4 m wide and runs rather slowly although there were some small rapids. The temperature of the water was 27º C. The river bed consisted of a mixture of sand and small stones. Emersed on banks in the river and on the river banks themselves were large stands of C. albida (NJ 77-81 a-k). The plants growing on open soil often had darker green or more reddish leaves while those growing close together and in the shade had lighter green leaves. Every transition between green leaves and marbled, red-brown were found. The leaves were more or less upright or flat on the ground, depending on the intensity of the light, those in full sun being flat on the ground.