植物界中所有生物的統稱，由多細胞、真核的生命形式組成（參閲eucaryote），六項基本特徵為︰幾乎均通過光合作用取得營養；分生組織能無限制的生長；細胞壁含纖維素，因此多少較為堅韌；缺乏運動器官；缺乏感覺器官和神經系統；生活史中顯現世代交替。沒有一個定義能完全排除所有非植物的生物體或包含所有的植物。例如，許多植物並非綠色，不能進行光合作用自制養料，而是寄生於其他活的植物體上（參閲parasitism），另一些則從死亡的生物體獲取營養。許多動物具類似植物的特徵，例如缺乏移動能力（如海綿）或生長方式類似植物（如某些珊瑚和苔蘚動物），但一般來説這些動物缺少上述的其他植物特徵。過去的一些分類系統（參閲taxonomy），將一些難歸類的類羣，如原生動物、細菌、藻類、黏菌和真菌（參閲fungus）歸入植物界，但這些生物體在形態上和生理上與植物有很大的不同，這使大部分科學家將它們畫出植物界。
plant
Any organism in the kingdom Plantae, consisting of multicellular, eukaryotic life forms (see eukaryote) with six fundamental characteristics: photosynthesis as the almost exclusive mode of nutrition, essentially unlimited growth at meristems, cells that contain cellulose in their walls and are therefore somewhat rigid, the absence of organs of movement, the absence of sensory and nervous systems, and life histories that show alternation of generations. No definition of the kingdom completely excludes all nonplant organisms or even includes all plants. Many plants, for example, are not green and thus do not produce their own food by photosynthesis, being instead parasitic on other living plants (see parasitism). Others obtain their food from dead organic matter. Many animals possess plantlike characteristics, such as a lack of mobility (e.g., sponges) or the presence of a plantlike growth form (e.g., some corals and bryozoans), but in general such animals lack other plant characteristics. Some past classification systems (see taxonomy) placed difficult groups such as protozoans, bacteria, algae, slime molds, and fungi (see fungus) in the plant kingdom, but structural and functional differences between these organisms and plants have convinced most scientists to classify them elsewhere.
