Lithophytes

Lithophyte is a plant that grows on rocks or in rocky crevices, deriving water and nutrients from rain, dust, and the mineral substrate. The term comes from Greek lithos 'stone' and phyton 'plant'. Lithophytes can be herbaceous or woody and may form rosettes or cushions.

Adaptations include shallow, strongly anchored root systems, cushions or mats that trap moisture, reduced leaves or succulent tissues to conserve water, and tolerance of high light and temperature fluctuations. Some lithophytes use CAM photosynthesis.

Habitats and distribution: Lithophytes occur in temperate and tropical zones, especially in alpine and desert rocks, on cliff faces, rocky outcrops, and limestone walls. They occupy microhabitats that offer crevices and trapped organic material, providing moisture and nutrients despite limited soil.

Reproduction and growth: Many lithophytes propagate vegetatively via offsets, stolons, or rhizomes; seed germination commonly requires cracks in rock or accumulated organic matter. Growth is typically slow, reflecting the challenging conditions in which these plants live.

Examples: Among the better-known lithophytes are Sedum (stonecrops), Sempervivum (houseleeks), Saxifraga (rock saxifrages) and Jovibarba.

Conservation and human use: Lithophytes are popular in rock gardens and green walls. In the wild, rocky habitat disturbance, quarrying, urban development, pollution, and climate change threaten some species, necessitating habitat protection and horticultural propagation to aid conservation.