three-cornered jack

Noun

three-cornered jack (plural three-cornered jacks)

1. (Australia) A weed of species Emex australis.
   • The “Three-cornered jack/Devils thorn” (Emex australis) is believed to be poisonous to them, as many dead locusts are found near to each plant.1901, South Australian Department of Agriculture, South Australian Department of Industry, Journal of Agriculture and Industry of South Australia, Volume 4, page 385
   • Many chemicals are being tested at Mildura in an attempt to control some of the more difficult weeds such as hard-head thistle (Centaurea repens) and three cornered jack/Devils thorn (Emex australis).1963, Victorian Department of Agriculture, The Journal of Agriculture, volume 61, page 504

   Synonyms:

   devils thorns, doublegee, spiny emex, bindi, bindi-eye, bindii, cathead, cat's head, doublegee

2. A seed vessel of this plant, which has three symmetrically arranged thorns and a pointed head.