(Encyclopedia) peppergrass, any species of the genus Lepidium, widely distributed peppery-tasting herbs of the family Cruciferae (or Brassicaceae; mustard family). They commonly have toothed leaves,…
(Encyclopedia) pickerelweed, common name for the Pontederiaceae, a family of chiefly tropical perennial aquatic herbs found in freshwater. The pickerelweeds (genus Pontederia) range north into…
(Encyclopedia) baby's breath, name for a plant of the family Caryophyllaceae (pink family) and for several other flowers, e.g., white bedstraw of the family Rubiaceae (madder family) and grape…
(Encyclopedia) ailanthusailanthusālănˈthəs [key], any tree of the genus Ailanthus, native to the warm regions of Asia and Australia. Ailanthus wood is sometimes used for cabinetmaking and for the…
(Encyclopedia) agrimonyagrimonyăgˈrĭmōˌnē [key], any plant of the genus Agrimonia, perennials of the family Rosaceae (rose family) native to north temperate zones, to Brazil, and to Africa. They are…
(Encyclopedia) ageratumageratumăjˌərāˈtəm, əjĕrˈə– [key] [Gr.,=unaging], any plant of the genus Ageratum, tropical American annuals of the family Asteraceae (aster family). The commonly cultivated…
(Encyclopedia) white snakeroot, North American woods perennial (Eupatorium urticifolium) of the family Asteraceae (aster family), having a flat-topped cluster of small white flowers. It is of the…
(Encyclopedia) blackthorn or sloe, low, spreading, thorny bush or small tree (Prunus spinosa) of the plum genus of the family Rosaceae (rose family), having black bark, white flowers, and deep blue…
by Liz Olson photos by Carol M. Highsmith A city rich in culture and diversity, San Francisco sits on a hilltop overlooking the Pacific Ocean. Millions have entered San Francisco Bay in…
Dinosaurs lived throughout the Mesozoic Era, which began 245 million years ago and lasted for 180 million years. It is sometimes called the Age of the Reptiles. The era is divided into three…
