LeafA leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, flower, and fruit collectively form the shoot system. In most leaves, the primary photosynthetic tissue is the palisade mesophyll and is located on the upper side of the blade or lamina of the leaf but in some species, including the mature foliage of Eucalyptus, palisade mesophyll is present on both sides and the leaves are said to be isobilateral.
Plant taxonomyPlant taxonomy is the science that finds, identifies, describes, classifies, and names plants. It is one of the main branches of taxonomy (the science that finds, describes, classifies, and names living things). Plant taxonomy is closely allied to plant systematics, and there is no sharp boundary between the two. In practice, "plant systematics" involves relationships between plants and their evolution, especially at the higher levels, whereas "plant taxonomy" deals with the actual handling of plant specimens.
Urtica dioicaUrtica dioica, often known as common nettle, burn nettle, stinging nettle (although not all plants of this species sting) or nettle leaf, or just a nettle or stinger, is a herbaceous perennial flowering plant in the family Urticaceae. Originally native to Europe, much of temperate Asia and western North Africa, it is now found worldwide. The species is divided into six subspecies, five of which have many hollow stinging hairs called trichomes on the leaves and stems, which act like hypodermic needles, injecting histamine and other chemicals that produce a stinging sensation upon contact ("contact urticaria", a form of contact dermatitis).
UrticaUrtica is a genus of flowering plants in the family Urticaceae. Many species have stinging hairs and may be called nettles or stinging nettles, although the latter name applies particularly to Urtica dioica. Urtica species are food for the caterpillars of numerous Lepidoptera (butterflies and moths), such as the tortrix moth Syricoris lacunana and several Nymphalidae, such as Vanessa atalanta, one of the red admiral butterflies. The generic name Urtica derives from the Latin for sting.
RosalesRosales (roʊˈzeɪliːz) is an order of flowering plants. It is sister to a clade consisting of Fagales and Cucurbitales. It contains about 7,700 species, distributed into about 260 genera. Rosales comprise nine families, the type family being the rose family, Rosaceae. The largest of these families are Rosaceae (90/2500) and Urticaceae (54/2600). The order Rosales is divided into three clades that have never been assigned a taxonomic rank.
Cronquist systemThe Cronquist system is a taxonomic classification system of flowering plants. It was developed by Arthur Cronquist in a series of monographs and texts, including The Evolution and Classification of Flowering Plants (1968; 2nd edition, 1988) and An Integrated System of Classification of Flowering Plants (1981) (see Bibliography). Cronquist's system places flowering plants into two broad classes, Magnoliopsida (dicotyledons) and Liliopsida (monocotyledons). Within these classes, related orders are grouped into subclasses.
CannabisCannabis (ˈkænəbɪs) is a genus of flowering plants in the family Cannabaceae. The number of species within the genus is disputed. Three species may be recognized: Cannabis sativa, C. indica, and C. ruderalis. Alternatively, C. ruderalis may be included within C. sativa, all three may be treated as subspecies of C. sativa, or C. sativa may be accepted as a single undivided species. The genus is widely accepted as being indigenous to and originating from Asia.