Because the criteria are matters of degree (normally of height) rather than of kind, the definition of a subshrub is not sharply distinguishable from that of a shrub; examples of reasons for describing plants as subshrubs include ground-hugging stems or low growth habit. Subshrubs may be largely herbaceous though still classified as woody, with overwintering perennial woody growth much lower-growing than deciduous summer growth. Some plants described as subshrubs are only weakly woody and some persist for only for a few years. Others, such as Oldenburgia paradoxa live indefinitely (though is still vulnerable to external effects), rooted in rocky cracks.
Achamaephyte, subshrubordwarf-shrub is a plant that bears hibernating buds on persistent shoots near the ground – usually woody plants with perennating buds borne close to the ground, usually less than 25 centimetres (9.8 in) above the soil surface. The significance of the closeness to the ground is that the buds remain within the soil surface layer and are thus somewhat protected from various adverse external influences. Accordingly, the chamaephyte habit is especially common in stressful environments, for example:
^Harris, James G.; Harris, Melinda Woolf (2001). Plant identification terminology: an illustrated glossary (2nd ed.). Spring Lake, Utah: Spring Lake Publishing. p. 117.
^Jackson, Benjamin, Daydon; A Glossary of Botanic Terms with their Derivation and Accent; Published by Gerald Duckworth & Co. London, 4th ed 1928
^Dennis M. Gorsuch; Steven F. Oberbauer; Jack B. Fisher; Dennis M. Gorsuch; Steven F. Oberbauer; Jack B. Fisher (2001), "Comparative Vessel Anatomy of Arctic Deciduous and Evergreen Dicots", American Journal of Botany, 88 (9): 1643–1649, doi:10.2307/3558409, JSTOR3558409, PMID21669698
^Molau, U.; Nordenhall, U.; Eriksen, B. (2005), "Onset of flowering and climate variability in an alpine landscape: a 10-year study from Swedish Lapland", American Journal of Botany, 92 (3): 422–31, doi:10.3732/ajb.92.3.422, PMID21652418