Phymatarum borneense M.Hotta

• Genus: Phymatarum
• Botanical Background: Described by Mitsuru Hotta in 1965 in Mem. Coll. Sci. Kyoto Imp. Univ.

• Geographical Range: Endemic to central and northern Sarawak (Malaysia) and Brunei, Borneo.
• Environment: Rheophytic on muddy riverbanks in lowland wet tropical forests; occasionally terrestrial in permanently saturated soils under deep shade.

Leaves

• Broadly oblanceolate to narrowly elliptic (12–25 cm × 2.5–8 cm), thick‑membranous, glossy dark green above and paler beneath, with purplish venation

Inflorescence (Spadix & Spathe)

• Solitary to three per shoot
• Spathe 6–9.5 cm long, constricted at midpoint, lower portion greenish, limb cream‑pink and reflexed
• Spadix 5–7 cm long with distinct female, sterile, and male zones

Growth Habit

• Terrestrial to rheophytic herb with creeping, rooting rhizomes
• Stems up to 40 cm long

Light Requirements

• Bright, indirect light
• Avoid direct sun

Watering & Humidity

• Keep substrate constantly moist
• High humidity (>70%)

Soil & Potting Mix

• Use acidic, well‑draining mix (peat‑based with perlite)

Temperature & Fertilizer

• Maintain 22–28 °C
• Feed monthly during growing season with balanced liquid fertilizer

Division and Cuttings

• Divide creeping rhizomes in spring
• Rreplant sections in moist medium

Seeds

• Rarely used
• Require warm, humid conditions and light germination medium

Typical Issues

• Susceptible to root rot (overwatering), spider mites, and mealybugs 
• Ensure good drainage and regular inspection

Treatment Recommendations

• Remove affected tissue
• Apply neem oil for pests
• Use diluted fungicide for root rot

• A true rheophyte adapted to fast‑flowing streams

• One of few Araceae endemic to Borneo

• Valued for compact habit
• Unusual inflorescence
• Rarity among collectors

Wild Population Status

• Predicted as threatened due to restricted range and habitat specificity

Market Availability

• Rare in trade
• primarily available through specialty nurseries and aroid societies