We are following the treatment in Robert P. Adams et al 'Taxodium (Cupressaceae); One, Two or Three Species? Evidence from DNA Sequences and Terpenoids' Phytologia (August 2012) 94(2) 159-168; in which Taxodium is treated as a monotypic genus - the single species having three vars distichum; imbricarium (Nutt.) Croom; and mexicanum (Carrière) Gordon. In some other treatments up to three distinct species are recognized - Taxodium distichum (L.) Rich; Taxodium ascendens Brongn.; and Taxodium mucronatum Ten.

Common Name: Swamp Cypress

General Information

Taxodium distichum is an evergreen to deciduous tree depending on the environment in which it grows. The straight trunk is enlarged basally, it can be up to 400cm in diameter and is often conspicuously buttressed; the crown is conic when young, often becoming irregularly flattopped or deliquescent (branched and so divided that the main axis cannot be determined) with age; it can grow up to 50 metres tall, though is usually smaller[]. The young shoots are of two kinds: (1) the leading ones, which are persistent and have the leaves spirally arranged; (2) the others, very slender, annual, and falling away in autumn along with the leaves; this latter kind of shoot has no buds[].
The tree produces a valuable, very durable timber and is harvested from the wild on a commercial basis. The tree is also harvested from the wild for local use as a medicine, and is widely grown as an ornamental.
Although commonly exploited for timber, this species is still widespread and abundant. The plant is classified as 'Least Concern' in the IUCN Red List of Threatened Species(2013)[].

Known Hazards

None known

Botanical References

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Range

Southern and eastern N. America - New Jersey to Florida, also southern Missouri and Illinois to Alabama, Texas, Mexico and Guatemala

Habitat

Wet sites that are under water for at least part of the year[], and often overlying calcareous soils[]. Often found where the water is brackish[].

Properties

Conservation Status	Least Concern
Medicinal Rating
Other Uses Rating
Habit	Deciduous Tree
Height	30.00 m
Growth Rate	Fast
Pollinators	Wind
Cultivation Status	Wild

Cultivation Details

Taxodium distichum is a plant of the temperate to tropical zones, growing at low elevations in the temperate zone but gradually ascending to around 2,000 metres or more as it moves into the tropics[, , ]. It grows best in areas where annual daytime temperatures are within the range 20 - 30°c, but can tolerate 8 - 34°c[]. When dormant, the plant can survive temperatures down to about -10°c or more depending on provenance, but young growth can be severely damaged at -1°c[, ]. It prefers a mean annual rainfall in the range 1,200 - 1,400mm, but tolerates 1,000 - 1,600mm[]. Plants grow best in areas with warm summers[].
Although this plant can be grown in wet soils and shallow water, it thrives in any soil and trees actually grow faster in normal unflooded soils[]. Established plants succeed in standing water up to 90cm deep[, ] - in such a situation the roots develop 'knees', curious cone-shaped structures that grow above the ground[]. Tolerates the high pH of chalk streams[]. Prefers a pH in the range 5.5 - 7, tolerating 4.5 - 8.5[]. Tolerates atmospheric pollution[]. Plants are tolerant of occasional very strong winds and are rarely blown over, even in a hurricane[].
Taxodium distichum is divided into three distinct vars :-
var distichum. The largest and hardiest form of the tree, with specimens up to 50 metres tall and, especially along the Mississippi Valley, tolerant of temperatures falling to around -30°c[, ].
Var imbricarium. Growing up to 30 metres tall, this form is restricted to southeastern N. America.
Var mexicanum. Growing around 30 metres tall, this form is found from Texas southwards through Mexico to Guatemala. It is the least hardy form, and probably the best one if you want to grow it in more tropical climates.
Swamp cypress is a fairly vigorous tree, it can grow up to 45cm in a year with up to 4cm increase in girth[]. It has been planted for its timber in southern Europe, especially on alluvial soils[].
Buds often begin to break in early spring, but trees do not come properly into leaf until early summer and growth in height rarely starts before early to mid summer[].
Often grown as an ornamental, when planted on the shores of lakes and ponds it will often develop 100cm tall 'knees' from its root system along the water's edge, adding to the interest of this species. It also grows well on higher ground away from water, where 'knees' will not develop[].
A very healthy species in Britain, rarely seen in anything but good health. It seems to be a very long-lived tree in this country with several specimens more than 250 years old[]. Trees are thought to live for over 1,000 years in the wild[].
Tree generally only produce fertile seeds after long hot summers[].
The branches are brittle and subject to wind damage, but the tree usually recovers well[].
Unlike most conifers, this species responds well to coppicing, even when old[, ].

Edible Uses

None known

Medicinal

The resin in the cones is used as an analgesic for wounds[, ].

The following uses were specifically for the var mexicana, though they should also be applicable to the other forms of this species.

A gummy resin produced after the tree is wounded has been used to cure skin diseases, wounds, ulcers, gout, and toothaches[].

Pitch produced by burning woodchips in a reducing atmosphere has been used as a cure for bronchitis[] .

The leaves have been used as a relaxant and a cure for itching[].

The bark has been used as a diuretic and an emmanagogue[].

Agroforestry Uses:

In its native riparian habitat, this species is increasingly recognized as a keystone species in swamp forest ecosystems providing both food and nesting opportunities for rare birds and other wildlife and as a natural regulator of floods[]. Riverine swamps of bald cypress reduce damage from floods and act as sediment and pollutant traps as they cause floodwaters to spread out, slow down, and infiltrate the soil[].
The tree has potential for rehabilitating margins of surface-mined lakes. Cypress domes can serve as tertiary sewage treatment facilities for improving water quality and recharging groundwater[].
It has also been planted as a water tolerant tree species used for shading and canopy closure in mosquito control programs[].

Other Uses

The bark has been used to make cordage[].

The wood is light, soft, not strong, moderately hard, easily worked, straight grained, extremely durable in damp soil, takes a good polish. It weighs 28lb per cubic foot[]. The wood is not given to excessive warping or shrinking[], it is used for construction, water pipes, vats etc[, , , , , , ]. The wood is widely used in construction and building of houses, boats, river pilings and sidings, as well as shingles, flooring, garden furniture, greenhouses, cooperage, fencing and other uses for which durability is desirable[].
The wood of the var mexicana is light or dark brown or yellowish and takes a good polish. It is soft and rather weak, but in Mexico it is esteemed for construction purposes, especially because it is resistant to decay and insect attacks[].

Propagation

Seed - sow late winter in a cold frame. When they are large enough to handle, prick the seedlings out into individual pots and grow them on in the greenhouse for at least their first winter. Plant them out into their permanent positions in late spring or early summer, after the last expected frosts.
If sowing a lot of seed you could sow it in early spring in an outdoor seedbed[]. Allow the plants to grow on in the seedbed for two years and then plant them into their permanent positions in late autumn or early spring.
Cuttings of extension growths in the late summer root quite easily[].