romantic grasses of the week: MORE LOVELY WEED FOR THE #ELECTION2013 campaign. PANICUM MAXIMUM or Megathyrsus maximus or megathyrsus infestus, common name guinea grass. a tall tussock 6ocm to 1.5m at maturity, main axis of panicle inflourescence can be up to 25cm long, oblong or pyramind.. often purplish in colour 900,000 seeds/kg. flowers the WHOLE year...Originates from Tanzania, Kenya. Can spread by rhizomes or stolons..