选C，像这种情况下grow是指植物的自然生长，不用plant被栽种，也不用被动.
plant / grow
这两个动词都有"种"的意思，区别如下：
1) plant"种植"，及物或不及物均可，常指移植已长成秧苗的植物，可用于"plant+场地+with"结构。如：
They planted trees in the garden. = They planted the garden with trees. 他们在花园里种树。
April is time to plant. 四月是种植季节。
2）grow"栽培；（人或草本等）生长"，及物或不及物均可，常指使某种植物从种子起在某地生长，不移走。如：
They grow roses in the greenhouse. 他们在温室里栽培玫瑰花。
Do all plants grow from seeds? 所有的植物都从种子长成的吗？
3) 指种植花草，用grow或plant均可；指种植树木，一般用plant；指种植农作物，用grow。如：
We have grown / planted a lot of flowers this summer. 我们夏天栽培了许多花。
People in the south grow rice. 南方人种植水稻。
Plants
Plants are very important living things. Life could not go on if there were no plants. This is because plants can make food from air, water and sunlight. Animals and man cannot do so. Animals get their food by eating plants and other animals. Man gets his food by eating plants and animals, too. Therefore, animals and man need plants in order to live.
If you look carefully at the plants around you, you will find that there are many types of plants. Some plants are large while others are small. Most plants are green.
There are two main types of plants: flowering plants and nonflowering plants.
Flowering plants have roots, stems①, leaves, flowers and fruits. Almost all the trees around us are flowering plants. You can probably recognize some plants from their flowers or their fruits.
Nonflowering plants include coniferous trees, mosses, liver-worts, algae and fungi. You cannot see many nonflowering plants around you.
Most plants do not grow from seeds. They grow from spores. Spores are very, very small. Some spores are so small and light that they can float in the air. We may say that spores are quite similar to seeds. When these spores fall on wet and shady② places, they usually grow into new plants.
①stem [stem] n． 茎；（树）干；（叶）梗
②shady[’sheidi] a．背阴的；阴凉的
1．coniferous a．针叶树的 2．moss n．苔藓；地衣3．liver-wort n．欧龙牙草 4．algae n．水藻；海藻 5．fungi n．真菌 6．spore n．孢子
