''Taxodium'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of one to three

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

(depending on taxonomic opinion) of extremely

flood A flood is an overflow of water ( or rarely other fluids) that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are an area of study of the discipline hydrol ...

-tolerant conifers in the cypress family, Cupressaceae. The generic name is derived from the

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

word ''taxus'', meaning " yew", and the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

word ''εἶδος'' (''eidos''), meaning "similar to." Within the family, ''Taxodium'' is most closely related to Chinese swamp cypress (''Glyptostrobus pensilis'') and

sugi ''Cryptomeria'' (literally "hidden parts") is a monotypic genus of conifer in the cypress family Cupressaceae, formerly belonging to the family Taxodiaceae. It includes only one species, ''Cryptomeria japonica'' ( syn. ''Cupressus japonica'' ...

(''Cryptomeria japonica''). Species of ''Taxodium'' occur in the southern part of the North American continent and are

deciduous In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, ...

in the north and semi-evergreen to

evergreen In botany, an evergreen is a plant which has foliage that remains green and functional through more than one growing season. This also pertains to plants that retain their foliage only in warm climates, and contrasts with deciduous plants, whic ...

in the south. They are large

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...

s, reaching tall and (exceptionally ) trunk diameter. The needle-like leaves, long, are borne spirally on the

shoot In botany, a plant shoot consists of any plant stem together with its appendages, leaves and lateral buds, flowering stems, and flower buds. The new growth from seed germination that grows upward is a shoot where leaves will develop. In the sp ...

s, twisted at the base so as to appear in two flat rows on either side of the shoot. The

cones A cone is a three-dimensional geometric shape that tapers smoothly from a flat base (frequently, though not necessarily, circular) to a point called the apex or vertex. A cone is formed by a set of line segments, half-lines, or lines conn ...

are globose, diameter, with 10-25 scales, each scale with 1-2

seed A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiospe ...

s; they are mature in 7–9 months after

pollination Pollination is the transfer of pollen from an anther of a plant to the stigma of a plant, later enabling fertilisation and the production of seeds, most often by an animal or by wind. Pollinating agents can be animals such as insects, birds, a ...

, when they disintegrate to release the seeds. The male ( pollen) cones are produced in pendulous racemes, and shed their pollen in early spring. ''Taxodium'' species grow

cypress knees A cypress knee is a distinctive structure forming above the roots of a cypress tree of any of various species of the subfamily Taxodioideae, such as the bald cypress. Their function is unknown, but they are generally seen on trees growing in sw ...

, when growing in or beside water. The function of these knees is currently a subject of ongoing research.

Species

The three extant

taxa In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...

of ''Taxodium'' are treated here as distinct species, though some botanists treat them in just one or two species, with the others considered as varieties of the first described. The three are distinct in

ecology Ecology () is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere level. Ecology overl ...

, growing in different environments, but hybridise where they meet. *†''

Taxodium dubium ''Taxodium'' is a genus of one to three species (depending on taxonomic opinion) of extremely flood-tolerant conifers in the cypress family, Cupressaceae. The generic name is derived from the Latin word ''taxus'', meaning "yew", and the Greek ...

'' (Sternb.) Heer

Formerly placed here

* ''

Glyptostrobus pensilis ''Glyptostrobus pensilis'', known in Chinese as 水松 (Shuǐ sōng), and also Chinese swamp cypress, is an endangered conifer, and the sole living species in the genus ''Glyptostrobus''. Description It is a medium-sized to large tree, reaching ...

'' (Staunton ex D.Don) K.Koch (as ''T. japonicum'' var. ''heterophyllum'' Brongn.) * ''

Sequoia sempervirens ''Sequoia sempervirens'' ()''Sunset Western Garden Book,'' 1995:606–607 is the sole living species of the genus '' Sequoia'' in the cypress family Cupressaceae (formerly treated in Taxodiaceae). Common names include coast redwood, coastal ...

'' (D.Don) Endl. (as ''T. sempervirens'' D.Don)

Uses

The trees are especially prized for their

wood Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin ...

, of which the

heartwood Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin t ...

is extremely rot- and

termite Termites are small insects that live in colonies and have distinct castes (eusocial) and feed on wood or other dead plant matter. Termites comprise the infraorder Isoptera, or alternatively the epifamily Termitoidae, within the order Blatto ...

-resistant. The heartwood contains a

sesquiterpene Sesquiterpenes are a class of terpenes that consist of three isoprene units and often have the molecular formula C15H24. Like monoterpenes, sesquiterpenes may be cyclic or contain rings, including many unique combinations. Biochemical modificat ...

called cypressene, which acts as a natural

preservative A preservative is a substance or a chemical that is added to products such as food products, beverages, pharmaceutical drugs, paints, biological samples, cosmetics, wood, and many other products to prevent decomposition by microbial growth or by ...

. It takes decades for cypressene to accumulate in the wood, so lumber taken from old-growth trees is more rot resistant than that from second-growth trees. However, age also increases susceptibility to Pecky Rot fungus (''

Stereum ''Stereum'' is the type genus of the Stereaceae family of fungi, in the Russulales order. Until recently, the genus was classified in the Corticiaceae family, of the Corticiales order. However, it was given its own family as a result of the spl ...

taxodii''), which attacks the heartwood and causes some damaged trees to become hollow and thus useless for timber. Bald Cypress wood was much used in former days in the southeastern United States for

roof shingle Roof shingles are a roof covering consisting of individual overlapping elements. These elements are typically flat, rectangular shapes laid in courses from the bottom edge of the roof up, with each successive course overlapping the joints below. ...

s. The shredded bark of these trees is used as a

mulch A mulch is a layer of material applied to the surface of soil. Reasons for applying mulch include conservation of soil moisture, improving fertility and health of the soil, reducing weed growth and enhancing the visual appeal of the area. A mu ...

Evolution

Fossil-leaf Taxodium dubium Tertiary Germany

In earth's history ''Taxodium'' was much more widespread in the Northern Hemisphere than today. The oldest fossils were found in

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...

deposits from North America. The trees persisted in Europe until around 2.5 million years ago, during the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Bükkábrány mummified forest

References

External links

Gymnosperm Database - TaxodiumCorkscrew Swamp Sanctuary website
*National Audubon Society, undated. ''Corkscrew Swamp Sanctuary. A Companion Field Guide''. Artype Inc., Ft. Myers. 25 p. {{Taxonbar, from=Q147392 Extant Late Cretaceous first appearances Conifer genera Deciduous conifers