PHILODENDRON CALLOSUM
PROTOLOGUE: Philodendron callosum , published in Das Pflanzenreich 4, Fam. 23 Db: 28 (1913). The protologue is reproduced below.
DISTRIBUTION: N. South America to N. Brazil: Brazil North, French Guiana, Guyana, Venezuela.
SPECIES DESCRIPTION:
Translated from protologue: Stem shortened. Petiole of the leaves stout, slightly flattened above and rather deeply channelled, 2.8–3.5 dm long, 1.5–2 cm thick below, slightly attenuate upward, narrowly sheathing in the lower third or quarter; blade rigid, thickly leathery, somewhat glossy above, lanceolate to lanceolate-oblong, at the apex shortly and obliquely cuspidate-acuminate, gradually narrowed toward the base and at the very base slightly blunted, 3–5 dm long, 1.2–1.6 dm wide, traversed on both surfaces by very numerous, very dense, more or less equal lateral nerves that leave the midrib at an obtuse angle (the intermediate ones at a very obtuse angle) and arch upward toward the margin, distinctly prominent, the midrib 6–9 mm wide below and narrowing upward.
INFLORESCENCE:
Translated from protologue: Peduncle terete, moderately stout, 8–10 cm long, 8 mm thick. Spathe whitish, or toward the base green on the outside and pale purplish within; its tube broadly ovoid, 3.5 cm long and nearly as wide, the blade ovate-oblong, shortly apiculate at the apex, 4.5–5 cm long, 4 cm wide. Spadix borne on a stipe 6–8 mm long, the female zone cylindric, 1.8–2 cm long, 1 cm thick, the male zone subclaviform and obtuse at the apex, 5–6 cm long, at the base as thick as the female or a little thicker, narrowing upward. Pistils ovoid-oblong, crowned by a small, circular, raised stigma, about 2 mm long and 1.5 mm thick, plurilocular with few-ovuled locules. Male flowers 2–4-androus.
ETYMOLOGY:
From Latin callosus, “hardened, thick-skinned, callous” (from callus, “hardened skin”). Although the original description does not explicitly explain the name, it most likely refers to the rigid, thickly leathery leaf blade described in the protologue.
NOTES:
1. Krause published this species from cultivated material. The protologue records it as introduced from Demerara, in British Guiana (now Guyana), and grown in botanical gardens; no wild locality or elevation was given.
2. The epithet had already circulated in horticulture: Krause placed the garden names Philodendron callosum Hort. and Philodendron schillerianum Hort. in the synonymy of the species.
3. Eduardo G. Gonçalves remarked in 2000, in a reply to a plant identification request on the Aroid-L mailing list, that Philodendron callosum is a plant of Venezuela and northern Brazil that usually grows in exposed patches over white sand or on rocky outcrops.⁴
REFERENCES:
1. Plants of the World Online, Royal Botanic Gardens, Kew — Philodendron callosum
2. Das Pflanzenreich IV.23Db (Heft 60): 28 (1913) — protologue.
3. iNaturalist: Philodendron callosum
4. Aroid-L mailing list, Eduardo Gonçalves, June 26th, 2000
Additional photos by David Scherberich
Additional photos by Patrick Blanc