Sandpainting is the art of pouring coloured sands, and powdered pigments from minerals or crystals, or pigments from other natural or synthetic sources onto a surface to make a fixed or unfixed sand painting. Unfixed sand paintings have a long established cultural history in numerous social groupings around the globe, and are often temporary, ritual paintings prepared for religious or healing ceremonies. This form of art is also referred to as drypainting.
Rangoli, a popular form of Indian sand paintings, in Singapore.
SLNSW 75764 Warriors in Ambush series 49 Aboriginal Mystic Bora Ceremony
Navajo sandpainting, photogravure by Edward S. Curtis, 1907, Library of Congress
Navajo sandpainting, photo by H.S. Poley, published c. 1890–1908, Library of Congress
Pollen is a powdery substance produced by most types of flowers of seed plants for the purpose of sexual reproduction. It consists of pollen grains, which produce male gametes. Pollen grains have a hard coat made of sporopollenin that protects the gametophytes during the process of their movement from the stamens to the pistil of flowering plants, or from the male cone to the female cone of gymnosperms. If pollen lands on a compatible pistil or female cone, it germinates, producing a pollen tube that transfers the sperm to the ovule containing the female gametophyte. Individual pollen grains are small enough to require magnification to see detail. The study of pollen is called palynology and is highly useful in paleoecology, paleontology, archaeology, and forensics.
Pollen in plants is used for transferring haploid male genetic material from the anther of a single flower to the stigma of another in cross-pollination. In a case of self-pollination, this process takes place from the anther of a flower to the stigma of the same flower.
Colorized scanning electron microscope image of pollen grains from a variety of common plants: sunflower (Helianthus annuus), morning glory (Ipomoea purpurea), prairie hollyhock (Sidalcea malviflora), oriental lily (Lilium auratum), evening primrose (Oenothera fruticosa), and castor bean (Ricinus communis).
Triporate pollen of Oenothera speciosa
Pollen of Lilium auratum showing single sulcus (monosulcate)
Arabis pollen has three colpi and prominent surface structure.