Cryptomeria: A plant genus of the family TAXODIACEAE. Its POLLEN is one of the major ALLERGENS.Taxodium: A plant genus of the family TAXODIACEAE. Members contain taxodione and taxodone, which are diterpenoid quinone methide tumor inhibitors.Pollen: The fertilizing element of plants that contains the male GAMETOPHYTES.Cambium: A layer of living cells between the bark and hardwood that each year produces additional wood and bark cells, forming concentric growth rings.Antigens, Plant: Substances found in PLANTS that have antigenic activity.Gymnosperms: Gymnosperms are a group of vascular plants whose seeds are not enclosed by a ripened ovary (fruit), in contrast to ANGIOSPERMS whose seeds are surrounded by an ovary wall. The seeds of many gymnosperms (literally, "naked seed") are borne in cones and are not visible. Taxonomists now recognize four distinct divisions of extant gymnospermous plants (CONIFEROPHYTA; CYCADOPHYTA; GINKGOPHYTA; and GNETOPHYTA).Diterpenes, Abietane: A group of DITERPENES cyclized into 3-ring PHENANTHRENES.Coniferophyta: A plant division of GYMNOSPERMS consisting of cone-bearing trees and shrubs.Plant Components, Aerial: The above-ground plant without the roots.Wood: A product of hard secondary xylem composed of CELLULOSE, hemicellulose, and LIGNANS, that is under the bark of trees and shrubs. It is used in construction and as a source of CHARCOAL and many other products.SesquiterpenesRhinitis, Allergic, Seasonal: Allergic rhinitis that occurs at the same time every year. It is characterized by acute CONJUNCTIVITIS with lacrimation and ITCHING, and regarded as an allergic condition triggered by specific ALLERGENS.Allergens: Antigen-type substances that produce immediate hypersensitivity (HYPERSENSITIVITY, IMMEDIATE).Trees: Woody, usually tall, perennial higher plants (Angiosperms, Gymnosperms, and some Pterophyta) having usually a main stem and numerous branches.