Polyscias guilfoylei 'Roble'

Roble aralia: native range and history

Botanists treat Polyscias guilfoylei as a cultigen: a plant whose identity developed through generations of selection and propagation. Its earliest associations extend from the islands of eastern Malesia into the south-west Pacific. It is now widespread in tropical cultivation, especially as a woody hedge, boundary and garden plant in wet-tropical regions.

Its earliest geography has become intertwined with generations of cultivation and transport. Food, medicinal, social and environmental uses all encouraged people to keep propagating it. ‘Roble’ is an ornamental selection from this longstanding cultivated stock.

Care for woody plants in containers

Feeding and propagation: Use dilute balanced fertiliser during active growth. Stem or cane cuttings and air layers can produce new plants, but warm, airy rooting conditions are essential.

Light: Polyscias ‘Roble’ grows best in bright, filtered light and can adapt to some gentle sun. Deep shade produces loose growth and leaf loss, while abrupt intense exposure can scorch.

Temperature: Use a humus-rich mix opened with coarse particles. Water the full root ball, allow the upper layer to partly dry, then water again according to current light and temperature.

Health checks for Polyscias guilfoylei 'Roble'

Polyscias ‘Roble’ may shed foliage after temperature changes, relocation or root disturbance. A bare stem is not necessarily dead: lightly inspect for firm green tissue and healthy buds rather than repeatedly cutting it back. Keep warmth, light and watering stable. If stems soften from the base or the root ball stays wet without using water, remove decayed roots and reduce the volume of saturated mix.

Fixed tan patches on the exposed side follow abrupt sun, while crisp margins across the crown more often indicate drought or dissolved salts. Flush salts only when drainage is free and the roots are functional. Do not flood a damaged root system. New unmarked leaves under stable filtered light are the best evidence that the cause has been corrected.

Inspect stems and leaf stalks for fixed bumps, cottony wax or sticky residue. Fine stippling and webbing across the leaflets point to mites. Once a pest is confirmed, keep the plant apart from nearby foliage. Clear away visible insects and apply an appropriate treatment to the woody joints and leaf undersides. Continue monitoring new growth and avoid assuming old feeding marks mean that treatment has failed.

Polyscias guilfoylei ‘Roble’ is toxic to cats and dogs

• Keep this plant away from cats and dogs that may chew it.
• It contains saponins that can irritate the mouth and digestive tract.
• Chewing may cause drooling, vomiting, stomach pain, reduced appetite or weakness. Contact a veterinarian if symptoms develop.

Who first published Polyscias guilfoylei, and what does the name mean?

Polyscias combines Greek polys, many, with skia, shade, parasol or canopy. The species epithet guilfoylei honours William Robert Guilfoyle.

Johann Reinhold Forster and Johann Georg Adam Forster established the genus Polyscias in 1776 in Characteres Generum Plantarum, second edition, page 63.

William Bull first described it as Aralia guilfoylei in 1873 in Gardeners’ Chronicle, volume 1873, page 606. Liberty Hyde Bailey later placed it in Polyscias as Polyscias guilfoylei in 1916 in Rhodora, volume 18, page 153.