Here the micropyle, chalaza and funicle are in a straight line. This is the most primitive type of ovule, e.g. piper, polygonum, cycas.

It is effective mechanical tissue of growing organs where it can give strength and elasticity.

Middle lamella is colloidal in nature. It is composed of magnesium and calcium pectate.

These are found in the stem and leaf sheaths of many monocots particularly grass.

Velamen is a spongy, multiple epidermis that covers the roots of some epiphytic or semiepiphytic plants, such as orchids.

Companion cell is specialized parenchyma cell, located in the phloem of flowering plants.

When phloem and cambium are present on both sides of xylem, the vascular bundles are called bicollateral vascular bundles.

The older, nonliving central wood of a tree or woody plant, usually darker and harder than the younger sapwood. It is also called duramen.

A tangential section is a longitudinal section of a stem where the section is perpendicular to the tangent or radius of the stem.

Here, solid core of xylem is surrounded by phloem.

Cleistogamy or automatic self-pollination describes the trait of certain plants to propagate by using non-opening, self-pollinating flowers.

Plant structure that develops into a seed when fertilized is called ovule. It is typically located inside the portion of the flower called the gynoecium.

A cytoplasmic organelle specialized for carrying out oxidative reactions. It does not contain DNA.

The earliest vascular plants had stems with a central core of vascular tissue. This consisted of a cylindrical strand of xylem, surrounded by a region of phloem. Around the vascular tissue there might have been an endodermis that regulated the flow of water into and out of the vascular system. Such an arrangement is termed a protostele.

Embryo sac is the female gametophyte in which the diploid embryo develops.