T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network

Eleusine tristachya (Three spiked goose grass)

Kingdom: Plantae
(unranked): Angiosperms
(unranked): Monocots
(unranked): Commelinids
Order: Poales
Family: Poaceae
Subfamily: Chloridoideae
Genus: Eleusine
Species: E. tristachya
Binomial name: Eleusine tristachya
Synonyms: Cynosurus tristachyos, Eleusine barcinonensis, Eleusine barcinonensis var. Mixta
Common names: Three-spiked goosegrass, Threespike goosegrass, Goose Grass, Crabgrass

Eleusine tristachya is an annual invasive summer weed that is native to Brazil, Bolivia, Paraguay, Uruguay, Argentina, and Chile including the Juan Fernandez Islands. It is now widely naturalised elsewhere. In New Zealand, it has been reported from Whanganui, Carteron, Gisborne, Hasting, Taupo and Napier. It habitats are dry sandy waste areas and lawns. It was probably introduced to New Zealand in imported grass seed. In some countries, it was introduced as a wool alien.

Eleusine tristachya is a tufted annual with a graminoid habit (elongate leaves and minute flowers). It grows up to 14–20 cm high. The long leaves are blade flat or folded, 2–4 mm wide, glabrous, parallel venation and with minutely scabrous on margins. 
Its culms are oblique or ascending, striate, compressed and are smooth. The inflorescences of Eleusine tristachya are arranged in 2–3 racemes of spikelets comprising 6–13 fertile florets. The spikelets are narrow-ovoid, laterally compressed; 5–9 mm long; 4–6 mm wide. The fruit is a caryopsis (grain).


A culm with two inflorescences

A culm with three inflorescences.

A culm with three inflorescences with spikelets that have small flowers.

Thanks to Wikipedia for text and information: https://creativecommons.org/licenses/by-sa/3.0/