Etymology: The specific epithet is derived from the dark brown to almost dark purple rachis of the leaves of living plants. Historical notes: Distinguishing features: Distribution and habitat: Ranging from north-central Colombia to Amazonian Colombia. It grows in wet to semidry lowland forest. Conservation status: Zamia melanorhachis is known from only three widely spaced localities. Its paucity in collections may well represent the fact that it is found in poorly explored areas. This is supported somewhat by the fact that it grows well and regenerates in an near native gardens. Not listed in the 1997 IUCN Red List of Threatened Plants. Description:
Stem subterranean and tuberous, 5-8 cm diam. Cataphylls triangular basally, linear-lanceolate apically, 2-5 cm long, 1-2 cm wide. Leaves 2-5, erect, oblong, 50 cm long; petiole terete, to 25 cm long, dark purple to black when fresh, armed with very small prickles; rachis terete, usually armed with very small prickles in lower one-half, to 20-30 cm long, 4-10 pairs of leaflets. Leaflets papyraceous, lanceolate, acute at apex, cuneate at base, margins serrate in upper two-thirds, 12-15 cm long, 1-2 cm wide. Pollen cones cream to tan, ovoid, 1-3 cm long, 0.5-1 cm diam.; peduncle 30-50 cm long; microsporophylls with both abaxial and a few (1-3) adaxial sporangia. Seed cones wine-red to dark red-brown, cylindrical to ovoid- cylindrical, 5-8 cm long, 3-4 cm diam. Seeds
red, 1-1.5 cm long, 0.5-0.8 cm diam.
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