Hoya clemensiorum (Sumatra)

Identity and natural origin of Hoya clemensiorum (Sumatra)

Hoya clemensiorum (Sumatra) is a cultivated line from Sumatra circulated under the name Hoya clemensiorum.

Accepted Hoya clemensiorum is native to Borneo, so the botanical identity of the Sumatra line is still uncertain. Its precise collection site within Sumatra and its selection history are also unknown.

Care for Hoya clemensiorum (Sumatra)

Light and support. Give the long stems a trellis in bright indirect light. Keep them out of intense light and hot sun.

Temperature and humidity. Use roughly 16–24 °C for normal growth, with protection from sustained cold under 10 °C. Humidity around 60–80% supports steady growth.

Potting mix and watering. Use an airy, chunky mix in a pot with drainage holes. Wait until the pot feels light and the mix is nearly dry throughout. Check moisture deeper in the mix with a skewer or through a clear pot. Then soak the root ball and let it drain. When growth slows, keep using the same nearly-dry-throughout cue; drying will take longer.

Feeding. During new growth, use balanced orchid fertiliser about every two weeks, at a modest dose.

Repotting. Move up one pot size once the root ball is crowded, securing the support again as the plant is repotted.

Propagation. Use a clean blade to take a healthy stem cutting with at least one healthy node. Root the lower, leafless node in lightly moist, airy propagation mix with the remaining foliage above it. Keep the cutting warm in bright indirect light and humid air until it has developed a healthy root system, then pot it into an airy mix.

Common problems with Hoya clemensiorum (Sumatra)

• Soft, yellowing foliage with persistently wet mix: Persistent wetness can damage roots. Drain trapped water and inspect roots if decline continues. If you find a small amount of root rot, use a clean, disinfected tool to cut the soft roots back to firm, healthy tissue. Throw away the rotten roots and old mix. Repot in fresh, airy mix, using a clean pot just large enough for the roots that remain. The pot must have drainage holes. If decay is widespread, save only healthy stem cuttings. Discard the plant if no healthy stems remain, and disinfect your tools afterwards.
• New crisp or bleached patches facing the light: Hot sun or a sudden increase in light can scorch leaves. When the colour changes, look for new crisp or bleached patches on the light-facing leaves and check whether exposure has recently increased. Move the plant into bright, filtered light. If you later move it to a brighter position, introduce the stronger light gradually. Existing dry patches will not recover; retain healthy foliage.
• Cottony insects at nodes and leaf joints: Confirm mealybugs beneath the wax and isolate the plant. Remove visible insects with a damp swab or tweezers. Inspect sheltered leaf joints, stems, the pot and any support weekly, removing any mealybugs you find until none remain. If mealybugs persist, use a product approved for home use against mealybugs on indoor ornamental plants in your country. Follow the label for how much to use, where to apply it, when to repeat treatment and all safety precautions.

Hoya clemensiorum (Sumatra) is non-toxic to people and pets

• This plant is non-toxic to people, cats and dogs.
• Chewing a large amount can still cause an upset stomach.
• If a large amount is eaten and symptoms continue, contact a veterinarian or medical professional.

Who first published Hoya clemensiorum, and what does the name mean?

Hoya honours the English gardener Thomas Hoy. Hoya clemensiorum commemorates the collectors Joseph and Mary Strong Clemens, whose extensive Bornean work supplied important botanical material.

Robert Brown established the genus Hoya in 1810 in Prodromus Florae Novae Hollandiae, page 459.

Ted Green first described Hoya clemensiorum in 2001 in Fraterna, volume 14, issue 3, page 12.