Mikania cordata

Name and classification

Mikania cordata (Burm. f.) Robinson
Family Asteraceae, Tribe Eupatorieae

Common names

mile-a-minute, African mile-a-minute

Disseminule

fruit

Description

Fruit an achene, narrowly oblanceolate, often slightly curved, 2–3.5 mm long, 0.4–0.5(0.75) mm in diameter, with 5 light brown longitudinal ribs; cross section 5 sided, sides +/– concave. Surface blackish-brown, minutely granular, with few to many conspicuous drops of amber resin. Scar basal, a short, tawny, narrow, irregularly cylindrical collar. Pappus one row of 40–45 ivory to light reddish-brown finely barbed bristles, 4–5 mm long. Pappus mostly persistent. Style base inconspicuous. Apex horizontal, blackish-brown, granular. Embryo spatulate, cotyledons minimally expanded; endosperm absent.

Identification considerations

Similar species

Ageratina adenophora (Sprengel) R. King & H. Robinson (=Eupatorium adenophorum Sprengel)

Ageratina riparia (Regel) R. King & H. Robinson

Mikania micrantha Kunth

Mikania scandens (L.) Willd. (non-FNW)

Distribution

African tropics and South Africa, Indian subcontinent and China through Southeast Asia to the Pacific Islands

native to Southeast Asia and the Pacific Islands

Habitat

tropics, prefers damp soil; a weed along rivers and streams, of forest borders and clearings, open disturbed areas, roadsides, tree plantations

General information

Mikania cordata is a rapidly-growing, creeping or twining perennial vine up to 10 m long, considered a more serious weed than M. micrantha. It twines around young tree crops, smothering them and forming dense, tangled masses. Propagation is by the wind-borne achenes, but vegetative reproduction is probably the more important means of spread. Roots can form at stem nodes, and even on small stem fragments with a single node. Stem fragments can be dispersed by cultivation and other means. Mikania cordata contains a substance that inhibits growth of other plants.

achene

achene

achene, detail

achene, detail

A, achene; B, achene outline showing entire pappus; C, longitudinal section showing embryo; D, transection of achene; drawing by Lynda E. Chandler

A, achene; B, achene outline showing entire pappus; C, longitudinal section showing embryo; D, transection of achene; drawing by Lynda E. Chandler

apex of achene

apex of achene

scar of achene

scar of achene