plöntunnar

Plöntunnar (plants) are a diverse group of organisms that capture light energy through photosynthesis and form the base of most ecosystems. They range from microscopic algae to the world’s tallest trees and inhabit oceans, soils, and the atmosphere. Common features include multicellular structures, rigid cell walls made of cellulose, chlorophyll pigments, and the ability to synthesize sugars from light, water, and carbon dioxide.

Anatomy and growth: Most plants have roots that absorb water and minerals, stems that support the plant, and leaves where photosynthesis occurs. In vascular plants, specialized tissues (xylem and phloem) transport water, nutrients, and sugars. Plants grow by cell division and elongation, and tissue development enables the formation of roots, stems, and leaves.

Reproduction and life cycles: Plants often show alternation of generations, alternating between a multicellular diploid sporophyte and a multicellular haploid gametophyte. Some reproduce via spores, others via seeds enclosed in fruits. Pollination and seed dispersal promote genetic diversity and distribution.

Diversity and evolution: Plants include non-vascular forms such as mosses and liverworts, seedless vascular plants like ferns, gymnosperms such as conifers, and angiosperms (flowering plants). They likely originated from green algae and adapted to terrestrial environments over hundreds of millions of years.

Ecology and human relevance: Plants are primary producers, converting light energy into chemical energy and releasing oxygen. They underpin food webs, provide food, medicines, fibers, timber, and aesthetic value, and play key roles in carbon cycling. Conservation of plant diversity is important for ecosystem resilience and climate regulation.