Lessons 1–3 · 3 lessons · O. Pratov, A. Tukhtaev, F. Azimova, I. Saparboev, M. Umaraliyeva. Biology (Botany), Grade 6. O‘zbekiston Publishing House, Tashkent, 2017
3
Life forms of plants
Textbook: pp. 8–11
GoalDistinguish plant life forms and give an example of each.
New words
tree · daraxtshrub · butasubshrub (semi-shrub) · yarimbutaannual, biennial and perennial herbs · bir yillik, ikki yillik, ko‘p yillik o‘tlar
Explanation
The outward form of a plant that has adapted to its environment is called its life form. A tree is a tall perennial with one thick woody trunk (apple, apricot, walnut, poplar). A shrub is a perennial with several woody stems (dog rose, pomegranate, blackcurrant). A subshrub has a stem woody only at the base; its green upper part dies back in winter (wormwood, winterfat, sarsazan). In perennial herbs the above-ground part dies in winter and the buds overwinter underground (alfalfa, dandelion, tulip). Biennial herbs make vegetative organs and store food in the first year and bloom and fruit in the second (carrot, beet, cabbage). Annual herbs germinate, bloom, fruit and finish their life within one year (wheat, cotton, sunflower, tomato).
Worked examples
Carrot is biennial: in the first year it makes leaves and an orange storage root; the flowering stem grows in the second year.
Wormwood (Artemisia) is a subshrub; alfalfa (Medicago sativa) is a perennial herb; dog rose (Rosa canina) is a shrub; poplar (Populus) is a tree.
Class activity
“Life-form walk”: divide the class into 6 groups. Each group finds 3 examples of its life form in the schoolyard or in pictures and writes them on the board. The most accurate and varied list wins.
Practice
1
What is the main difference between a tree and a shrub?
A tree has one thick trunk; a shrub has several woody stems.
2
Group these: sunflower, carrot, pomegranate, winterfat (izen), dandelion, plane tree (chinor).