ive ▁tram pling ▁and ▁p ud d ling . ▁It ▁can ▁be ▁controlled ▁in ▁some ▁European ▁locations ▁by ▁increasing ▁available ▁pot ass ium ▁and ▁ph osph orus , ▁increasing ▁stock , ▁and ▁impro ving ▁d rain age . ▁These ▁rem ed ies ▁are ▁not ▁as ▁effective ▁in ▁North ▁America . ▁ ▁No x ious ▁we ed ▁Hol cus ▁lan atus ▁is ▁a ▁significant ▁p est ▁we ed ▁in ▁Australia , ▁as ▁it ▁is ▁a ▁winter - g row ing ▁C 3 ▁grass ▁and ▁surv ives ▁dr ought s ▁and ▁hot ▁sum mers ▁as ▁seed . ▁It ▁is ▁dist aste ful ▁to ▁stock ▁unless ▁it ▁is ▁young ▁and ▁little ▁other ▁plant ▁material ▁is ▁available . ▁The ▁flowers ▁are ▁wind - pol lin ated ▁and ▁usually ▁out - cross ing . ▁The ▁first ▁se eds ▁become ▁vi able ▁ 5 ▁to ▁ 9 ▁days ▁after ▁flow ering ▁and ▁all ▁are ▁vi able ▁after ▁ 2 0 ▁days . ▁Se eds ▁are ▁shed ▁from ▁in ▁summer ▁and ▁early ▁aut umn . ▁One ▁pan icle ▁has ▁ 1 0 0 ▁to ▁ 3 8 0 ▁se eds , ▁with ▁ 1 7 7 , 0 0 0 ▁to ▁ 2 4 0 , 0 0 0 ▁se eds ▁per ▁plant , ▁depending ▁on ▁time ▁of ▁emer gence . ▁ ▁In vas ive ▁species ▁In ▁North ▁America , ▁Hol cus ▁lan atus ▁is ▁an ▁invas ive ▁species ▁in ▁native ▁grass lands ▁and ▁other ▁e cos ystem s . ▁In ▁Y os em ite ▁National ▁Park ▁it ▁is ▁one