It is an annual herb producing a hairless, waxy stem up to a meter tall.

This is an annual herb with a decumbent or erect, hairless stem.

The mostly hairless stem is thick, hollow, and reddish in color.

This is an annual herb with a flanged, hairless stem.

It is an annual herb producing a hairless stem up to about 60 centimeters in maximum height.

It grows to 10-50 cm tall, with a single, erect, hairless stem, branching toward the top.

The hairy or hairless stem has occasional small lance-shaped leaves.

The branching, hairless stem grows to nearly 30 centimeters in maximum length.

It has a hairless reddish stem, containing a milky latex, growing from 30 to 200 cm.

The flowers are pale pink and the thin, hairless stem is reddish in color.