Dypsis decaryi Seeds | Triangle Palm
LATIN NAME: Dypsis decaryi
COMMON NAME: Triangle Palm
Plant Profile
The triangle palm has a trunk that is triangular in cross-section, a fact that is obvious from ten metres away and gives the plant its common name. It grows to six or eight metres, with three ranks of arching leaves and a skirt of dead leaf bases that hangs below the crown.
It comes from the dry south of Madagascar, where it survives on little rain, and it has become one of the most planted palms in tropical gardens from Florida to Thailand. Wild populations are small and the species is listed as vulnerable. The fruit is a small black drupe, and the seed inside is grooved, which is how the genus is separated from other Madagascar palms.
Science & Biotechnology
The triangular trunk comes from the way the leaf bases are packed: three columns of sheathing bases run up the stem in a spiral so tight that the trunk has three flat faces. The arrangement is a phyllotaxis of three ranks, unusual among palms, most of which show five or eight.
Its drought tolerance is structural rather than physiological. The leaves are stiff and coated, the dead bases insulate the growing point, and the roots go deep and wide. In cultivation the palm is more often lost to crown rot from overhead watering in cool weather than to dryness. The leaf bases are covered in a waxy bloom that gives the trunk a grey-blue cast and reflects a good part of the incoming light.
Uses & Benefits
The palm is planted as a specimen in tropical and subtropical gardens, in roundabouts and in hotel forecourts, where its geometry does the work of a sculpture. It is also grown in large containers on terraces, though a potted plant rarely reaches the size of one in the ground.
The seed is not eaten, and the trunk is not used for timber, since the wood is soft and fibrous. In Madagascar the plant has no significant local use beyond shade, which is one reason its decline went unnoticed for so long. Demand for seed is high and supply is erratic, since a single palm carries a few dozen fruit at most and the crop ripens over several months.
Growing from Seed
Sow fresh seed, since it loses viability within a few months, in a well-drained mix at twenty-five to thirty degrees. Germination is slow and uneven, from two to six months, and the first leaf is a strap rather than a fan.
Pot on before the roots circle, and plant out only when the trunk is a metre tall, since small plants are easily lost to rot in wet soil. Give full sun and a raised position, and water at the base rather than over the crown. In a cool climate grow it in a large pot and move it under cover for winter.
Our Take
The most architectural palm in the catalogue, and one that takes drought better than it takes kindness. Plant it where the trunk can be seen.
Related Reading
Readers interested in Triangle Palm frequently explore these as well: