Gyrocarpus jacquinii
A nice small caudiciform  from northern Thailand that grows on limestone cliffs.
 

Description: Due to it's wide distribution the Gyrocarpus americanus is a quite variable species. It is a small to medium slender, deciduous tree 2 to 18 m tall. The "jacquinii" is a shrubby form found in the Asian far east and usually it is characterized by a swollen caudiciform habit and reduced size. This Asian plant is grown sometimes by succulent enthusiasts since if forms a nice succulent trunk and can be grown in very small pots, making an attractive bonsai.
Caudex: The caudex of G. jacquinii is round to elongated, more or less ribbed and woody up to 20 cm in diameter. The Bark is pale grey/yellow-brown/white. Smooth/scaly, often bleaching to a silvery-white on the sunny side.
Leaf: Spirally arranged, alternate, crowded near the ends of branches, entire.ovate/palmate, more or less deeply 3-5 lobed, cuneate, acuminate, dark green above, paler greyish below, finely velvety on both surfaces, markedly 3-5 veined from the base; veins yellowish. The lamina is Medium/large. 4 - 25 × 2 - 22 cm. Petiole: 4 - 18 cm Stipules: Absent.
Flower: In terminal much branched cymes, yellowish-green with an unpleasant smell.
Fruit: Fruit a woody nut with 2 long. brown thin wings, aiding wind dispersal, hairy. 1.2 - 2 × 1.1 - 1.5 cm.
 

This is a caudiciform tree famous for its large seeds that whirl like the blades of a helicopter.

Gyrocarpus jacquinii Gaertner
De Fructibus et Seminibus Plantarum 2: 92, t. 97. 1791

Currently accepted Scientific name:   Gyrocarpus americanus Jacq. subsp. americanus  

Origin:  Old and New World Tropics. Americas, Africa, Asia and Oceania.

Habitat:  Grows in hot, dry  lowland and lowland forest often on rocky ridges and hillsides. Ecology:  Secondary grassland.

Conservation status: Not threatened.

Common English Names include: Helicopter Tree, Propeller Tree.

The foliage is reminiscent of a grape leaf.
 

Cultivation: It is easy to grow and puts on a fanciful display, but  it takes years to develop and  is not a plant for the impatient gardener. It needs a well-drained soil (e.g. use a mixture for cactus  + normal potting soil)  with the caudex planted largely above the soil surface. It needs regular watering during the active growing season without too much water. Let the soil become rather dry before watering again. Reduce watering gradually when the leaves dries out in autum, or else the caudex may rot. Restore normal watering frequrence when the leaves starts growing again in spring. Give it  plenty of sun, but keep the caudex bulb shaded. Protect from heat in summer. A clay pot is best.  It should be overwintered in the greenhouse at temperatures over 12°C (avoid letting temperatures drop lower than 5° C).