Dypsis decaryi Seeds | Triangle Palm
LATIN NAME: Dypsis decaryi
COMMON NAME: Triangle Palm
Plant Profile
A well-grown triangle palm explains its own name in a glance, because the crown is a prism rather than a shuttlecock of leaves. Dypsis decaryi holds its fronds in exactly three vertical ranks set a third of a circle apart, so the palm presents a clean triangle from whichever side you approach it. That geometry carried it out of southern Madagascar and into warm gardens worldwide.
Most large pinnate palms emit each new leaf at a fixed fraction of a turn from the last and build a spiral. This one repeats a single third, which botanists call tristichous. Leaflets held in a stiff V around the rachis make a frond almost a folded fan, and the leaf bases stay fixed on the trunk instead of being shed as a crownshaft.
The trunk is solitary, occasionally branching, and clothed in overlapping horseshoe-shaped scars from the fronds that preceded the present crown. On an old specimen the grey column looks carved rather than merely ringed. Growth is slow, so a tall trunk is a long investment, and the palms flower while still short, fruiting on plants barely above head height.
Wild triangle palms belong to the dry south-east of Madagascar, around the Andohahela massif and the coastal plain near Tolagnaro, on stony slopes and in low dry forest. The species is planted in enormous numbers across the tropics while the wild population shrinks, because the sisal estates laid out around Tolagnaro cleared much of the forest that held it.
The bluish-green of the fronds is surface, not pigment. Epicuticular wax over the leaflet epidermis is why the newest fronds are bluest and older ones read greener once it has been rubbed away. Seedlings in shade stretch and lose the colour, and a frond handled repeatedly in a nursery row shows a dull patch where the thumb has been.
Science & Biotechnology
Palms are slow and awkward from seed, and this species pushed nurseries toward laboratory methods. Because Dypsis seed is short-lived in storage, material is raised from very fresh seed or in vitro: zygotic embryo excision takes the embryo out of the oily endosperm, while somatic embryogenesis drives cells from young inflorescence or leaf tissue through embryo stages on auxin-rich media.
Uses & Benefits
The inflorescence is interfoliar, pushing out between the leaf bases rather than from below a crownshaft, and it branches to about three orders. Small yellow flowers are borne in triads of one female flanked by two males, the standard arecoid arrangement. Bees work the spikes, and the fruit that follows is small, dark and not a harvest crop.
Palm endosperm is an oil store, and across the family the storage lipid is dominated by saturated and monounsaturated fatty acids, palmitic and oleic acids as the bulk with linoleic acid as a smaller fraction. The oily, thin-coated seed is why this one stores badly in warm air and is best sown soon after harvest.
As an ornamental the palm wants a frost-free site in full sun and a position where all three faces show, so a lawn specimen suits it better than a crowded border. Established plants take drought, salt wind and poor soil. The fruits are not eaten and the palm heart is not worked commercially; the value of the tree is structural.
Growing from Seed
The southern dry formations, with their euphorbias and spiny Didiereaceae, impose hard light and a long rainless season. The palm answers with a heavy wax layer over the leaf surface, leaflets stiff enough to resist wind, and persistent frond bases that shield the growing point from sun and heat. In habitat it keeps its lowest fronds far longer than a watered garden plant.
In pots the palm needs a coarse free-draining mix and a container heavy enough not to blow over, because the trunk thickens at the base before it gains height. Palms answer strongly to potassium and magnesium, and the first sign of shortage is discolouration on the oldest fronds while the crown still pushes.
Sow fresh seed in deep tubes filled with two parts coir to one part perlite and a handful of coarse sand. Press each seed in so it sits roughly its own depth below the mix, water once, and keep the tray warm and faintly moist. The first organ above the mix is a strap-shaped eophyll, not a divided frond.
Move the seedling on once the eophyll has hardened and the second leaf is open, using a mix with extra grit, because the palm sends a deep sinker root down before it spreads. Overpotting is the common mistake: a small root ball in a large wet volume rots. Protect young plants from cold, which scars the trunk.
Our Take
Give a triangle palm the sunniest spot you own and the patience to let the trunk build. Where frost arrives, keep it in a pot under cover; our notes on the areca palm and the California fan palm cover companions for the same frame, and sabal palmetto suits colder ground.
Related Reading
Gardeners who grow Triangle Palm often pair it with these related subjects: