本文主要探討全採集之231個稗草樣品在形態、生育及對殺草劑敏感性上的變異情形，於抽穗後25日所調查莖桿分散的角度，可將所有樣品分為5種株型：直立型的所有分蘗桿為垂直線的角度小於30°，中間型及開放型則為45°和60°，另外散開型的角度大於60°但其分檗桿並不橫置於地面，至於匍伏型，其分蘗桿則完全爬行於地面，五種型中以直立型和匍伏型在本省分布最少，此外樣品間之葉數和抽穗期不論是在一期作或二期作的差異都很顯著，而其他性狀間的變化在兩期作間並不一致，至於對本省常用來殺稗草的三種萌前殺草劑、馬上除、掃丹、和樂滅草，都很敏感，不論任何一樣品，在幼苗期（播種後5至10天）都會被殺死。

Variation of morphology, growth and herbicide susceptiblity of island-wide collected 231 lines of barnyard grass were inves-tigated. All sampling lines could be divided into five plant types based on the culm angle at 25 days after heading : Erect, the angle was less than 30' from the erpendicular; Intermediate and Open were about 45' and 60', respectively; Spreading was more than 60' but the culms did not rest on the ground;and Procumbent, the culm or its lower part rested on ground surface. Among them, erect and procumbent types distributed scarcely in Taiwan. Data on number of leaf and date of heading time in all sampling lines showed different significantly either the first crop season or the second one. And the variation of other characters were not consistent in two crop seasons. As to susceptibilities of herbicides; butachlor. benthiocarb and oxadiazon recommended extensively used to control barnyard grass killed all sampling lines at their seedling stage (5 to 10 days after seeding).