Amorphophallus haematospadix: The Blood-Red Spadix Aroid of Limestone Forests

Among the more visually striking members of its genus, Amorphophallus haematospadix Hook.f. owes its evocative name to one of its most dramatic features: a deep reddish to dark purplish-black spadix that contrasts sharply with its creamy white spathe. Hooker formally described this limestone-dwelling species in 1893 in the Flora of British India. It grows on limestone outcrops in the northern part of the Malay Peninsula and southern Thailand. Two features make it uniquely identifiable in the genus: a clavate, blood-colored appendix and transverse ridges on the inner surface of the spathe base — a character combination found in no other congener. This article introduces the species to botanists, plant collectors, and curious readers interested in one of Southeast Asia’s more elusive aroids.

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Taxonomic Identity of Amorphophallus haematospadix

Amorphophallus haematospadix belongs to the family Araceae. Hooker described it in Fl. Brit. Ind. 6 (1893): 517. One synonym is currently recognized:

• Amorphophallus siamensis Gagnep.

This synonym reflects a later independent description of the same species under a different name, before the two names were consolidated.

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Morphological Description

Tuber and Leaf

The tuber of Amorphophallus haematospadix is depressed-globose to subglobose, measuring 2–12 × 2–9 cm. It produces a few annual offsets. These offsets are globose, fusiform, or obovate and measure 5–2 cm. The plant bears a single solitary leaf. The petiole is uniformly green or olive-green, smooth, and measures 50–85 cm long by 1–3 cm wide.

The leaf blade reaches 60–80 cm in diameter. Its rachises are broadly winged, except for the most proximal portions. Leaflets are lanceolate, 7–26 × 2–6.5 cm, acuminate, and leathery in texture. Their upper surface is dark green and moderately glossy. Venation is very dense, with secondary veins very closely spaced — a distinctive vegetative feature of this species.

Inflorescence and Peduncle

The inflorescence of Amorphophallus haematospadix is long-pedunculate. The peduncle appearance matches the petiole in color and texture, measuring 17–40 cm long by approximately 8 mm wide.

Spathe

The spathe is elongate-triangular, 8–21 cm long and 4–7 cm wide, and apiculate at the apex. The limb margins are strongly reflexed. Both the inner and outer limb surfaces are creamy to yellowish-white. The outer base transitions to a creamy or yellowish-white surface that becomes suffused with pale purplish-green toward the base. The interior of the spathe base is dark purple. Importantly, the base interior carries transverse ridges, with small punctiform warts between them. This combination of transverse ridges is unique within the genus and provides a reliable identification character for the species.

Spadix and Floral Zones

The spadix of Amorphophallus haematospadix is sessile. It is slightly longer than the spathe, measuring 9–22.5 cm. Occasionally the spadix may be slightly shorter. The pistillate (female) flower zone is shortly cylindrical, 7–10 cm long and 6–15 cm wide. Its flowers are congested.

The staminate (male) flower zone is cylindrical to slightly obconical, 7–15 × 1.3–2.5 cm. It also carries congested flowers. Staminate flowers carry 3–4 stamens each, and the stamens are dull dark blackish-purple.

The appendix is cylindrical-clavate, 8–19.5 × 1–2 cm. Its basal half is terete. The upper half is slightly fusiform and slightly laterally compressed, with a rounded apex. The color is glossy or dull reddish to dark greyish-black. A faint reddish-purple hue appears at the base. Additionally, the base bears several diamond-shaped, flattened staminodes. Some of these carry a small conical process.

Female Flowers

Each ovary is globose, measuring 2.5 × 2.5 mm, and creamy white in color. The style is slender, 2–3 mm long and 0.5 mm wide, and reddish-brown. The stigma is subglobose, 0.5 × 0.6–0.8 mm. It is entire or slightly bilobed, verruculose, and dark grey with rounded lobes.

Male Flowers

Male flowers carry 3–4 stamens each. Stamens are dull dark blackish-purple in color. No further detail on anther dimensions appears in the available protologue description.

Fruit not seen (description as in Boyce et al. 2012).

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Distribution of Amorphophallus haematospadix

Amorphophallus haematospadix grows in the northern part of the Malay Peninsula (West Malaysia) and in southern Thailand. A specimen in the Kew herbarium, collected under the name Sander s.n., also suggests a possible occurrence in North Sumatra. However, no additional material from Sumatra currently confirms this. As a result, the Sumatran presence remains unverified and cannot be fully ruled out.

For verified occurrence data and distribution records, refer to GBIF – Amorphophallus haematospadix and the Plants of the World Online (POWO) – Kew.

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Habitat

This species grows on limestone. It favors the alkaline, often coastal karst environments typical of Peninsular Thailand and West Malaysia. Its strict limestone substrate preference places it in the same ecological guild as other limestone-specialist aroids found throughout insular Southeast Asia.

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Taxonomic Notes

Amorphophallus haematospadix stands out clearly among Indonesian and Malesian aroids. Researchers recognize it by two features that occur together in no other species in the genus. First, the appendix is clavate and distinctively red to dark reddish-purple in color. Second, the inner surface of the spathe base carries unique transverse ridges. These two characters together allow instant field identification when the inflorescence appears.

Furthermore, a specimen at the Kew herbarium annotated as imported from Sumatra in June 1983 raises the possibility that the species may also occur in North Sumatra. However, Hetterscheid and Ittenbach (1996) noted that no additional confirming material exists. Consequently, the species distribution remains provisionally limited to the Malay Peninsula and southern Thailand, with Sumatra treated as uncertain.

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References

• Hooker, J.D. (1893). Amorphophallus haematospadix Hook.f. In: Fl. Brit. Ind. 6: 517.
• Boyce, P.C., Sookchaloem, D., Hetterscheid, W.L.A., Gusman, G., Jacobsen, N., Idei, T. & Nguyen, V.D. (2012). Flora of Thailand 11(2): 101–325. The Forest Herbarium, Bangkok.
• Hetterscheid, W.L.A. & Ittenbach, S. (1996). Everything you always wanted to know about Amorphophallus, but were afraid to stick your nose into! Aroideana 19: 7–131.
• Kew Science. Amorphophallus haematospadix Hook.f. – Plants of the World Online. Available at: https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:84360-1
• GBIF Secretariat. Amorphophallus haematospadix occurrence data. Global Biodiversity Information Facility. Available at: https://www.gbif.org/species/4933167