Hypericum species are quite variable in habit, occurring as trees, shrubs, annuals, and perennials. Trees in the sense of single stemmed woody plants are rare, as most woody species have multiple stems arising from a single base. Certain rarities occur in the section Camplyosporus, for example Hypericum bequaertii, growing upwards of 10 m (33 ft) from a single woody trunk. Shrubs have erect or spreading stems but never root from nodes that touch the ground. However, perennial herbs tend to root from these horizontal nodes, especially those that occur in wet habitats. Annual herbs tend to have taproots with a developed system of secondary hair roots. Many species of Hypericum are completely glabrous, others have simple uniseriate hairs, and some species have long, fine hairs.