• True succulent (or Primary stem succulents): Nonwoody plants  that have specialized fleshy, turgid, soft and juicy tissues designed for the conservation of large amounts water .
• Woody stem succulents: Plants with a woody support network with large parenchymatous gaps where large volumes of water can be stored.

In general succulents are plants that store water in their plant tissue, they may be loosely grouped as:

• Stem succulents: (most of which are cacti) plants the have swollen, moisture-retaining stems.
  (e.g. Pachypodium namaquanum)
• Leaf succulents: Plants that have foliage but often lack a stem, whereas cacti and other stem succulents have a swollen stem but mostly lack leaves. (e.g. Echeveria laui or many vygies, i.e. members of the family Mesembryanthemaceae – commonly referred to as mesembs)
• Root succulents: Plants the have swollen, moisture-retaining roots. (e.g. Pterocactus tuberosus)
• Caudiciforms & pachicauls: Plants the have swollen, moisture-retaining trunks. . (e.g. Uncarina grandidieri, Adansonia digitata)
• Bulbous: Plants that have swollen, moisture-retaining bulbs. (e.g. Ornitogalum caudatum)