Once a seed has made its home in the soil, its next step is to begin germination. But germination does not always occur right away. Seeds may remain dormant in the soil anywhere from a few weeks to many years.
Above the point of attachment of the cotyledons is a structure called the "epicotyl." Later, it gives rise to the upper part of the stem, the leaves, and the terminal bud.
An animated depiction of a bee pollinating a plant
An animated depiction of gymnosperm reproduction
In the sexual reproduction of ferns, spores are released into the air and eventually fall to the ground to form a prothallus in the gametophyte phase. The gametophyte produces eggs and sperm. The sperm swims to the egg and fertilization occurs.
An animated depiction of the sexual reproduction of moss
Angiosperms reproduce sexually when pollen from the male part of the flower is transferred to the female part of the flower, where an egg is fertilized and a seed develops.
Most leaves have an outer layer, called the epidermis, that protects and covers the leaf.
The mesophyll, located below the epidermis, is made of two layers - the palisade layer, made of cells instrumental in carrying out photosynthesis; and the spongy layer, which has many air cavities, in which gases from the plant and air mix.
Stomata are small holes that allow gases to flow in and out of the leaf.
Plants possess vascular tissue, which is a system of tiny tubes that move food and water throughout the plant.
Underneath the bark of a tree is a layer of phloem, which consists of tubular cells that move food from the leaves and stem throughout the body of the plant. Cambium, another type of vascular tissue, is responsible for making new xylem and phloem.
Roots lengthen at the root tip.
The place where two plates collide is called a convergent boundary.
This map of lithospheric crust indicates the directions in which plates are moving.
Divergent boundaries form when two plates separate.
Iceland straddles the Mid-Atlantic Ridge where the North American Plate and Eurasian Plate are moving away from one another.
The Juan de Fuca Plate is one of many smaller plates.
The lithosphere is made up of the crust and upper mantle.
Matching patterns of parallel magnetic stripes on either side of mid-ocean ridges, indicating that new ocean crust is being added at the same rate, support the notion of seafloor spreading.