🌿 Hoya rundumensis Splash — The Living Canvas of Borneo’s Mountains

Hoya rundumensis Splash is one of the most visually spectacular Hoya species with naturally variegated foliage, offering a permanent visual display thanks to the silvery-white splashes that adorn its leaves like paint droplets thrown by an abstract artist onto a deep green canvas. Native to Mount Rundum in the state of Sabah on the island of Borneo, this species grows in montane tropical forests at altitudes of 1,000 to 1,800 metres, where morning mist and persistent fog create a unique microclimate.

The Splash form was selected for the exceptional intensity of its silvery patterning, which varies from fine speckles to large, irregular patches, giving each leaf a unique, unrepeatable appearance. No two leaves are perfectly alike — each is a small masterpiece of nature, an original painting on a living botanical substrate that evolves as the plant grows.

For passionate collectors, Hoya rundumensis Splash represents an exceptional acquisition, combining botanical rarity with immediate visual impact. Unlike many variegated plants that require special conditions to maintain their patterning, this Hoya retains its silvery splash regardless of light conditions, because it is not an unstable genetic variegation but a natural species pattern encoded in its DNA.

Its montane adaptation grants it a surprising tolerance for cooler temperatures compared to other tropical Hoya species, making it particularly well-suited for cultivation in European apartments where temperatures never reach tropical extremes. It is a plant that brings the exoticism of Borneo’s virgin cloud forests directly into the living room.

🌍 Origin and Botanical History

Hoya rundumensis was described scientifically relatively recently, based on specimens collected from Mount Rundum (Gunung Rundum) in the Tenom district of Sabah, on the Malaysian part of Borneo. The species belongs to the family Apocynaceae, subfamily Asclepiadoideae, and is placed within the genus Hoya alongside other montane species from Borneo’s highland forests.

Mount Rundum, with its summit at approximately 1,860 metres, is part of the Crocker Range and harbours extraordinary biodiversity, including numerous endemic plant and animal species found nowhere else on Earth. The montane forests of this area are characterised by high humidity, moderate temperatures, and an abundance of mosses and lichens covering every available surface in a verdant, primeval tapestry.

The Splash form was identified and introduced into cultivation by specialised collectors from Malaysia who observed the natural variation of foliar patterning in wild populations growing on moss-covered tree branches. The term “Splash” describes the random pattern of silvery spots on the leaves, reminiscent of the “splatter painting” artistic technique. This form quickly became one of the most sought-after Hoya variants on the international rare plant market.

The natural distribution of the species is extremely limited, known only from a few localities in northern Borneo, which confers upon it a special rarity status. In cultivation, available specimens derive almost exclusively from vegetative propagation, ensuring the preservation of the characteristic Splash pattern from the mother plant through each generation of cuttings.

🌱 The Foliage

The leaves of Hoya rundumensis Splash are undoubtedly the primary motivation for this species being so highly sought after by collectors worldwide. Elliptic to ovate in shape, measuring 7 to 12 centimetres in length and 3 to 5 centimetres in width, the leaves display a unique pattern of silvery spots and splashes on a deep green background, like constellations scattered across the night sky.

The Splash pattern varies considerably from leaf to leaf — some have large, irregular patches covering up to 40 to 50 percent of the leaf surface, while others display fine, evenly dispersed speckles. This natural variability makes each specimen unique, and each newly unfurling leaf a delightful surprise. The silvery spots are created by microscopic air bubbles between cellular layers of the epidermis, which reflect light in a manner similar to the silvery scales of certain fish species.

Leaf texture is fleshy, succulent, with a thickness of 2 to 4 millimetres that gives them a pleasant firmness to the touch. The upper surface is slightly matte or with a subtle sheen, in contrast to the pronounced gloss of many other Hoya species. The midrib is visible, and lateral veins form a fine reticulate pattern visible in transmitted light, adding another layer of visual interest.

The petiole is short (1 to 2 cm), robust, and leaves are arranged oppositely on the stem, creating a decorative symmetrical effect. In specimens receiving bright indirect light, the silvery splashes become even more pronounced, and the green background may develop lighter nuances. New leaves unfurl with a delicate pinkish-beige hue that gradually transforms into the mature green adorned with the signature silvery constellation.

🌸 The Flowers

The flowers of Hoya rundumensis Splash are equally enchanting as the foliage, though more discrete in their beauty. Clustered in umbels of 8 to 15 individual flowers, they emerge from persistent peduncles at the axils of mature leaves along established stems. Each flower measures approximately 1 to 1.5 centimetres in diameter, with five petals of creamy yellow to light orange colour, possessing a waxy texture and glistening appearance.

The central corona is white-yellow with reddish nuances, creating a delicate contrast with the lighter petals that speaks to the refined beauty typical of montane Hoya species. The fragrance is sweet, with notes of honey and vanilla, moderate in intensity, most pronounced during the evening hours. The nectar produced by the flowers is abundant and translucid, adding a touch of glassy sparkle to the already charming umbels.

Flowering occurs predominantly during the warm season, though well-maintained specimens may bloom at other times of the year as well. Being a montane species, its tolerance for cooler temperatures means it does not require excessive warmth to initiate flowering — sometimes, a cooler period can actually be beneficial for bud formation. Floral peduncles are persistent and must never be cut after flowering.

First flowering typically occurs after 2 to 3 years of cultivation, once the plant has developed sufficient mature branching. Umbels form at nodes along mature stems, and a well-established plant can produce multiple inflorescences simultaneously, creating a refined display that perfectly complements the splash foliage beauty.

🌱 Growth Habit and Development

Hoya rundumensis Splash displays a compact twining habit, with semi-rigid stems that coil around supports or arch elegantly in hanging planters. Growth rate is moderate to slow, typical of montane species that in their natural habitat grow in cooler conditions with less solar energy available. In cultivation, it can add 20 to 40 centimetres of new growth per year under favourable conditions.

Branching is natural and generous, gradually creating a full, lush plant with many silvery splashes visible simultaneously. Adventitious roots form at nodes, anchoring the plant to its support medium. As a montane epiphyte, it prefers a very well-drained substrate with good air circulation in the root zone, mimicking the mossy branches where it grows in nature.

Its montane origin confers an important advantage in cultivation: tolerance of cooler nocturnal temperatures (down to 12–14°C) and a preference for moderate daytime temperatures (20–26°C). This adaptation makes it ideal for European apartments and homes where extreme tropical heat is not available year-round, making it one of the easier rare Hoyas to maintain in temperate climates.

• Light: Bright to moderate indirect light. The splash pattern is most visible under good light conditions. Avoid direct summer sun, which can bleach or scorch the leaves.
• Temperature: Optimal 18–26°C. Tolerates down to 12°C, being a montane species adapted to cooler highland conditions. Cooler nights (15–18°C) are beneficial for overall health.
• Watering: Allow substrate to dry completely between waterings. In winter, water every 10–14 days. Use room-temperature, lime-free water for best results.
• Humidity: 50–70% ideal. Montane species appreciate higher humidity levels. A humidifier or pebble tray with water helps considerably.
• Substrate: Mix of pine bark (40%), perlite (30%), sphagnum moss (20%), and charcoal (10%). Rapid drainage is essential for root health.
• Fertilising: Balanced liquid NPK fertiliser at half strength, once monthly from April to September during the active growth period.
• Propagation: By stem cuttings with 2 nodes, in water or moist sphagnum at 20–24°C. Rooting takes 4–6 weeks under favourable conditions.