Taxodium distichum, also known as Bald Cypress, Baldcypress or Swamp Cypress, is a species of conifer native to the southeastern United States, from Delaware Bay south to Florida and west to southern Texas, and also inland up the Mississippi and Ohio Rivers north to southern Illinois and Indiana.

It is a large tree, reaching 30-45 m tall and with a trunk diameter of up to 3 m. The leaves are spirally arranged but twisted at the base to lie in two horizontal ranks, 1-2 cm long and 1-2 mm broad; unlike most other cypresses, it loses the leaves in the winter months (hence the name 'bald'). The cones are green maturing gray-brown, globular, 2-3.5 cm in diameter, and disintegrate when mature to release the large seeds. The seeds are 5-10 mm long, the largest of any species in the cypress family, and are water-dispersed.

Bald Cypress occurs mainly along riparian (riverside) wetlands subject to periodic flooding by silt-rich 'brownwater' rivers, unlike the related Pond Cypress, which occurs in silt-poor blackwater rivers and ponds. Ancient Bald Cypress forests, with some trees over 1200 years old, once dominated swamps in the southeast US. The largest remaining stand of Bald Cypress is at Corkscrew Swamp Sanctuary, near Naples, Florida. These trees are around 500 years of age and some exceed 40m (130 ft) in height.

Bald Cypresses growing in swamps have a peculiarity of growth called cypress knees. These are woody projections sent above the water from the roots. One rather popular view of their function is that they provide oxygen to the roots that grow in the low dissolved oxygen (DO) waters typical of a swamp (see also mangroves, which have similar adaptations). However, there is little evidence for this; in fact, swamp-dwelling specimens whose knees are removed continue to thrive. Another more likely function is that of structural support and stabilization. Lowland, or swamp grown cypress which are flooded or flood prone, tend to be buttressed, as opposed to cypresses grown on higher ground which may grow with very little taper.

The natural northern limit of the species is not due to a lack of cold tolerance, but to specific reproductive requirements; further north, regeneration is prevented by ice damage to the year-old seedlings. If slightly larger young trees are planted, they are able to tolerate much lower temperatures, and can be grown as far north as Minnesota. It is also commonly planted elsewhere outside of its native range in other temperate regions of the world.

The Bald Cypress was designated the official state tree of Louisiana in 1963, and is considered by some to be a symbol of the southern swamps.

diagragm of root system of leylandii cypress tree

Cupressus × leylandii, is often referred to as just Leylandii. It is a fast-growing evergreen tree much used in horticulture, primarily for hedges and screens.

The Leyland Cypress is a hybrid between the Monterey Cypress, Cupressus macrocarpa, and the Nootka Cypress, Cupressus nootkatensis, family Cupressaceae. The hybrid has arisen on nearly 20 separate occasions, always by open pollination, showing the two species are readily compatible and closely related. Two other similar hybrids have also been raised, both involving Nootka Cypress with other Cupressus species:

-Cupressus arizonica var. glabra × Cupressus nootkatensis (Cupressus × notabilis)
-Cupressus lusitanica × Cupressus nootkatensis (Cupressus × ovensii)

The taxonomic status of Nootka Cypress is disputed; in the past, it was widely regarded as belonging in the genus Chamaecyparis, and in 2002 it was classified in a new genus Xanthocyparis. The most recent treatments (2004), however, transfer it to Callitropsis. In any of these treatments, the hybrids becomes very unusual in being intergeneric hybrids, the only ones ever reported among the Gymnosperms. In fact the very existence of these hybrids, and their ease of formation, is a further strong pointer (in addition to genetic and morphological evidence) for the treatment of Nootka cypress in Cupressus. It may be added that attempts to cross Nootka cypress with other Chamaecyparis species have been universally unsuccessful.

Where Nootka Cypress is treated in Chamaecyparis, the name of the hybrid becomes × Cupressocyparis leylandii, and where treated in Xanthocyparis, it becomes × Cuprocyparis leylandii.

Leyland Cypresses are commonly planted in gardens to provide a quick boundary or shelter hedge. However, their rapid growth (up to a meter per year), heavy shade and great potential height (often over 20 m tall in garden conditions, and they can reach at least 35 m) make them problematic. In Britain it has been the source of a number of high profile disputes between neighbours, even leading to violence (and in one recent case, murder), because of its capacity to cut out light. Part VI of the Anti-Social Behaviour Act 2003 introduced a way for people affected by high hedges (usually, but not necessarily, of leylandii) to ask their local authority to investigate complaints about the hedges, and gave the authorities power to have the hedges reduced in height.

It is poorly adapted to areas with hot summers, such as the southern half of the U.S.A., and in these areas becomes - perhaps fortunately - very prone to the disease cypress canker caused by the fungus Seridium cardinale. This causes extensive dieback and ultimately death of the tree. In California's Central Valley, they rarely live more than ten years before succumbing, and not much longer in southern states like Alabama. In these areas, the canker-resistant Arizona Cypress is much more successful.

In Northern areas where heavy snows occur, this plant is also susceptible to broken branches and even uprooting in wet, heavy snow.

Note: Caution should be exercised when handling tree clippings - after trimming, for example. The sap can cause skin irritation in susceptible individuals.

Widdringtonia is a genus of coniferous trees in the Cupressaceae (cypress family). There are four species, all native to southern Africa, where they are known in the past as "cedars" (to which they are not related) but are now known as African cypresses.

They are large shrubs or trees, reaching 5-20 m tall (to 40 m in W. whytei). The leaves are evergreen and scale-like, except on seedlings, which have needle-like leaves 1-1.5 cm long. The adult scale leaves are arranged in decussate opposite pairs in four rows along the twigs, while the juvenile needle leaves are arranged spirally.

The male cones are small, 3-6 mm long, and are located at the tips of the twigs. The female cones start out similarly inconspicuous, maturing in 18-20 months to 2-3 cm long and wide, globular to ovoid, with four, thick, woody scales, arranged in two opposite pairs. The cones mostly remain closed on the trees for many years, opening only after being scorched by a wildfire; this then releases the seeds to grow on the newly cleared burnt ground. In W. whytei the cones open soon after maturity to shed the seed without fire; this species is more sensitive to fire and only grows in moister situations where it is protected from fire. The best adapted to fire is W. nodiflora, which has the ability to re-grow from the roots, as well as by seed.