Because the criteria are matters of degree 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, 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 however, such as "Oldenburgia paradoxa" live indefinitely, rooted in rocky cracks.