Triabthena portulacastrum is an annual herb of the family Aizoaceae. The Desert Horse Purselane is succulent and usually glabrous.
- The stems of the Desert Horse Purselane are fleshy and prostrate. The stems are usually reddish.
- The leaves of the Desert Horse Purselane are opposite, simple, and obovate. There are small hairs near the leaves. They are petiolate.
- Triabthena portulacastrum flowers are tiny. Each flower has 5 lobes that open only in the morning. The flowers of the Desert Horse Purselane do not have petals, but the sepals are petallike.
- The blossoms of the plant occur on the leaf axils. The flowers are usually solitary and sessile.
