ALOCASIA MACRORRHIZOS

Species

Mar 4

Written By BostonJungle

ORIGINAL DESCRIPTION:

Robert Sweet, Hortus Britannicus., 3rd edition: (1839) P. 631

SYNONYMS:

Homotypic Synonyms: Arum macrorrhizon, Caladium macrorrhizon, Colocasia macrorrhizos

Heterotypic Synonyms: Alocasia cordifolia, Alocasia gigas, Alocasia grandis, Alocasia harrisii-pulchrum, Alocasia insignis, Alocasia marginata, Alocasia pallida, Alocasia plumbea, Alocasia rapiformis, Alocasia uhinkii, Arum cordifolium, Arum mucronatum, Arum peregrinum, Arum rapiforme, Caladium indicum, Caladium metallicum, Caladium plumbeum, Calla badian, Calla maxima, Colocasia boryi, Colocasia mucronata, Colocasia peregrina, Colocasia rapiformis, Philodendron peregrinum, Philodendron punctatum

DISTRIBUTION: Bismarck Archipelago, Borneo, Maluku, New Guinea, Philippines, Queensland, Solomon Is., Sulawesia

While native to the areas highlighted in green, *Alocasia macrorrhizos* has been widely introduced through the rest of Asia (highlighted in purple)

Native range within the Philippines, created by @the_bluebeeboo

CLIMATE: Tropical humid climate

Humidity is moderate throughout the year, ranging from 60% to 70%

Temperature is varies between the seasons - within the range of 48°F/9°C to 88°F/31°C during the day. Minimum temperatures never dip below 45°F/7°C

Rainy and humid season (October to May) and a dry season between June and October. The average annual rainfall is 1,200 mm

ECOLOGY: N/A

SPECIES DESCRIPTION:

Massive, evergreen pachycaul herb that can form a thick, erect trunk up to about 4 m tall, typically devoid of old leaf bases, and exudes slightly milky latex. The stem may be erect (to around 1.5 m) or decumbent. Leaves are produced in clusters, held more or less erect at the tips of stems in larger plants.

Petioles are stout, to roughly 1.3 m in length, and sheathing in their lower third to half. They are eglandular, with persistent sheath-wings that are straight to somewhat recurved.

Leaf blades are light green on both surfaces, generally sagittate to bluntly triangular (sometimes described as ovate-sagittate), reaching 70 cm to over 1 m long and 60–90 cm wide (occasionally recorded as up to 120 × 50 cm). The margin is entire to slightly sinuous. The anterior lobe bears about nine primary lateral veins on each side, diverging at approximately 60°, each with distinct axillary glands. Secondary venation is flush with the lamina or only slightly raised abaxially, not forming well-defined interprimary collective veins.

Posterior lobes measure roughly one-third to one-half the length of the anterior lobe, are somewhat rotund, and often overlap; in mature plants they are naked in the sinus, while in juveniles they can be weakly peltate. This robust, pachycaul growth habit, along with the sheathing petioles and large sagittate leaves, distinguishes Alocasia macrorrhizos in cultivation and in the wild.

INFLORESCENCE:

Inflorescences are produced in pairs among the leaf bases, each pair subtended by membranous cataphylls; the peduncle barely exceeds these cataphylls at anthesis. The spathe, 13–35 cm long, is constricted about one-sixth from the base, with the proximal portion green and ovoid. The spathe limb is broadly oblong to oblong-lanceolate, pale yellow, cowl-like at anthesis, then reflexed and eventually deliquescent, measuring about 10.5–29 cm.

The spadix is slightly shorter than the spathe, briefly stipitate, and divided into female, sterile, and male zones, terminating in an appendix. The female zone is conical-cylindrical, 1–2 cm long by about 1.5 cm in diameter, with roughly 30 pistils. Ovaries are pale green, unilocular, and 3 mm in diameter; the stigma is sessile, 3–5-lobed, conical-lobed, and yellow. The sterile zone (interstice) is white, composed of about four whorls, slightly shorter than or equaling the female zone, and constricted in alignment with the spathe’s own constriction.

The male zone is cylindrical, 3–7 cm long by about 2 cm in diameter, white or whitish; the synandria are rhomboid-hexagonal, slightly convex on top, and composed of 4–9 fused stamens, with the anthers opening via lateral slits that do not reach the apex of the synandrium. The appendix is yellowish, staminodial, slightly thicker than the male zone at its base, then tapering; it is at least half the length of the spadix and can considerably exceed that.

Upon fruiting, the spathe becomes green, oblong-ellipsoid, and about 8 cm long. The fruits themselves mature into scarlet to red, ellipsoid berries, roughly 12 × 8 mm, containing a few seeds. Seeds are pale brown, about 4 mm in diameter, and bear a small strophiole (strophiolate).

O: Young infructescence at Stage IV. P: A dissected infructescence filled with secretion in which Colocasiomyia larvae developed. Q: Developing infructescences at Stage V. R, S: A dissected infructescence with Colocasiomyia pupae in the spaces between fruits and the spathe tube. T: The top of an infructescence tightly enclosed with the spindle and the spathe tube (dissected). U: An infructescence starting to dehisce at Stage VI. V: A dissected infructescence with red mature fruits and Colocasiomyia puparia. W:Remains of an infructescence several days after dehiscence.

VARIEGATED FORMS: WHITE, YELLOW, GREEN

ETYMOLOGY:

Alocasia macrorrhizos features a specific epithet that might appear unusual to those expecting “macrorrhiza.” This naming, however, follows well-established principles of Greek-derived plant nomenclature, preserving both the original Greek root meanings and specific rules of Greek grammar that carry over into botanical Latin.

1. Basic Meaning and Greek Roots

Makros (μακρός) – Means “long” or “large.”
Rhiza (ῥίζα) – Means “root.”
When combined, they give the core idea of “having large/long roots.”

2. Why “macrorrhizos” Instead of “macrorrhiza”

Greek Grammatical Rules
- In Ancient Greek, the letter rho (ρ) at the beginning of a word is aspirated (written with a rough breathing mark) and is commonly transliterated as “rh.”
- When forming compound words where the second component begins with an aspirated rho (ῥ), Greek orthography doubles the rho (ῤῥ). This is done to preserve the aspirated sound and ensure proper pronunciation in Greek.
Doubling of the ‘r’
- Because the word “ῥίζα” (rhiza) starts with an aspirated rho, compounding it with “μακρός” (makros) triggers the rule that rho is doubled.
- As a result, “μακρός” + “ῥίζα” becomes μακρόρριζος in Greek, which transliterates to macrorrhizos in the Latin alphabet.
Botanical Latin Adaptation
- Latin does not normally use a rough breathing mark, nor does it aspirate the “r.” Still, botanical Latin retains many Greek orthographic conventions to reflect the original Greek form.
- Thus, the epithet remains macrorrhizos instead of “macrorrhiza,” mirroring the Greek rule and preserving the double “r.”

3. Gender, Euphony, and Consistency in Botanical Nomenclature

Greek compounds undergo vowel and consonant changes for euphony (smooth pronunciation) and grammatical agreement.
Botanical Latin, though a specialized form of Latin, often incorporates these Greek inflectional and phonetic nuances to maintain consistency with historical usage.
The suffix “-rhizos” thus aligns with the established pattern in Greek compound words referring to roots and is kept intact in the Latinized epithet.

4. Conclusion

The specific epithet macrorrhizos in Alocasia macrorrhizos is a faithful reflection of its Greek roots and associated grammatical rules. While it may look like it should be spelled “macrorrhiza,” the doubled “r” (and the “-rhizos” ending) is a direct carryover from the way Ancient Greek manages compound words beginning with an aspirated rho. These linguistic conventions explain why the correct spelling remains macrorrhizos rather than “macrorrhiza”—ultimately indicating a plant “with large roots,” just as the original Greek intended.

NOTES:

Alocasia odora ‘California’ often gets confused with Alocasia macrorrhizos, but an easy way to differentiate the two is by looking at the sinus insertion on the petiole, with Alocasia odora ‘California’ being semi-peltate. Additionally Alocasia odora ‘California’ at full size will be smaller than Alocasia macrorrhizos, and have a more oval leaf shape, while the lateral veins will be sunken as opposed to embossed in the Alocasia macrorrhizos.