Cyrtosperma johnstonii

Natural range of Cyrtosperma johnstonii

Cyrtosperma johnstonii is native to the Solomon Islands, including Vangunu and Vella Lavella in Western Province, where it grows at very low elevation beside streams.

It has been grown in Europe since the 1870s, when English nurseryman William Bull introduced it for its brightly veined young foliage.

How to grow Cyrtosperma johnstonii

• Water: Keep the potting mix wet while the plant is growing. In warm conditions, a broad pot can stand in shallow clean water; change that water regularly.
• Light: Give bright filtered light. An established plant can take gentle sun if you introduce it gradually.
• Potting mix: Use a rich mix that holds plenty of water and stays loose around the roots. Mix in bark, pumice or perlite to leave air spaces around the roots.
• Temperature: Warm conditions suit this species. Protect the plant from cold spells and from cold standing water.
• Humidity: Humid air suits the large leaves. Gentle airflow helps water dry from the leaves and centre of the plant.
• Feeding: Feed moderately while new leaves are growing. Rinse the potting mix with fresh water occasionally to reduce fertiliser salts.
• Handling: Wear sturdy gloves and give the plant enough space to avoid brushing against the prickled leaf stalks.
• Propagation: Well-rooted offsets can be separated once they have their own roots. It can also be grown from viable seed when fertile fruit is produced.
• Repotting: Repot when roots and offsets fill the container or the potting mix begins to break down.

Keeping Cyrtosperma johnstonii healthy

• Leaf edges dry and the leaves lose firmness: The plant may be short of water. Water the pot thoroughly and keep the potting mix consistently wet while protecting the foliage from hot dry air.
• Roots turn soft and the water or potting mix smells sour: Stagnant water or dense wet potting mix can damage the roots. Replace any standing water, remove damaged roots and cut soft dark tissue back to firm healthy tissue with a clean blade. Discard the rotten parts and repot in fresh potting mix if needed.
• Dark water-soaked patches appear after a cold spell: Chilling can injure the foliage. Move the plant to steady warmth and remove leaves only after the damaged tissue has clearly dried or collapsed.
• Silvery streaks, distorted new leaves or fine speckles appear: Thrips or spider mites may be present. Isolate the plant and inspect new leaves and their undersides. Treat for the pest you find according to the product label, then keep checking emerging leaves for new streaks, distortion or speckling.

Cyrtosperma johnstonii is toxic to people and pets

• Keep this plant away from children, cats and dogs.
• Its leaves and stems contain insoluble calcium oxalate crystals, which can irritate the mouth, throat, skin and eyes.
• Chewing may cause burning pain, drooling, swelling, vomiting or difficulty swallowing. Contact a veterinarian or medical professional after exposure, especially if swelling or breathing problems occur.

When and where was Cyrtosperma johnstonii first published?

Cyrtosperma combines Greek kyrtos, curved, with sperma, seed.

William Griffith established the genus Cyrtosperma in 1851 in Notulae ad Plantas Asiaticas, volume 3, page 149.

Thomas Moore and Maxwell Tylden Masters first described it as Alocasia johnstonii in 1876 in Gardeners’ Chronicle, new series, volume 5, page 603; William Bull had proposed that name. Nicholas Edward Brown later placed it in Cyrtosperma as Cyrtosperma johnstonii in 1882 in Gardeners’ Chronicle, new series, volume 18, page 808.