Leaves
Most Plants grow/get bigger
most plants grow in the a-horizon
seed
lots of plants, the pussyweed is the most common
do
No, most plants will not grow at all in salt water.
water
seed
Not all plants have roots (eg phytoplankton) and while some plants do grow form their roots (eg grasses), most plants do not grow from their roots but from their apical growing tip.
Some plants grow in winter. But most plants adaptations are to live in warm weather. Why? That's just so.
No plants grow in the North Pole because it is far too cold for anything to grow. Most plants need certain temperatures to sprout, along with soil.
Very few plants will grow in heavy clay soil and not many will grow in sand. Plants need organic material in the soil to enable the roots to penetrate and to nourish the plants, so the more humus soil contains, the better most plants will grow. Plants also do not thrive in very acid or highly alkaline soil. Most plants prefer neutral or slightly acid pH. Sne45: I think clay-like soil, nor do I think plants in sand can grow.