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Post by Peter on Dec 24, 2006 14:13:44 GMT 1
St Helena Redwood ( Trochetiopsis erythroxylon) is a tree endemic to St. Helena and is Extinct in the Wild. After settlers arrived on the island, the species was heavily exploited for its excellent timber and bark which was used for tanning hides. By 1718, the species was already extremely rare. Further losses occurred when flax plantations began in the late 1800s. By the mid 20th century, only one redwood survived and this single tree is the source of all the Redwoods known in cultivation today. Inbreeding depression and a depauperate gene pool form the most serious threat to the future survival of this species.  Photo © Rebecca Cairns-Wicks. www.iucnredlist.org/info/gallery2004extinctplants.petermaas.nl
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Post by Melanie on Dec 27, 2006 14:26:01 GMT 1
 Redwood (St Helena Redwood) Trochetiopsis erythroxylon This is a St Helena endemic species in an endemic genus (family Sterculiaceae). It differs from its relative the St Helena Ebony in being a more upright, medium-sized tree (up to at least 6 m) growing straight on suitable soil. It also has paler green leaves, which are green below with white-felted veins; the leaves turn red as they die. The flowers are generally borne in pairs and are about 40 mm across and pendulous, never opening widely; they are initially white but quickly turn rose pink and finally brownish red. The flowers have a weak but pleasant fragrance. The capsule is similar to that of the Ebony and contains 3-5 seeds. The bark is dark brown, even and fairly smooth, and the wood reddish-brown and close-grained. Flowers are produced over a long period in summer and are visited by many different moths and flies, but especially by the introduced honeybee. The Redwood produces abundant nectar and was probably originally pollinated by large endemic moths that may now be extinct. In former times the Redwood was common in the damp woodland just under the central ridge between 500 and 700 m above sea level, occupying the best land for plant growth in the island, along with the She-Cabbage Tree. It was still common in 1659 when the East India Company colonised the island, and since the wood is hard and durable, it was used by the settlers for building houses. The tree was also of great importance because its bark (like that of the Ebony) was suitable for tanning the hides of the cattle. As a result of these uses, and because it never regenerated easily, the Redwood quickly became very scarce. In about 1722 it was evidently with difficulty that Edward Byfield (who was later Governor) obtained a couple of young plants no more than an inch high and raised them to produce seed. The species seems to have been extensively planted after this, since in 1757 the St Helena Records note that the Queen Sophia was loaded "with Bale Goods, Pepper, Salt Petre, and Redwood, Bound for Copenhagen". Thereafter, the Redwood was found mainly in island gardens, but a few trees were known to grow in the wild, near Diana's Peak and High Peak. The last known wild tree grew near the base of the waterfall at Peak Gut; it died around 1960. Norman Williams (a retired Forestry Officer) used to collect seed from this tree, and resulting seedlings were planted at Scotland and other sites on the island. Later generations have been grown and planted at High Peak, Scotland, Stitches and Hardings by George Benjamin and the Endemic Section, and a good specimen grows at Mount Pleasant. However, a recent booklet on the endemic plants pointed out that the surviving individuals of the Redwood "are most unthrifty and even with the best care, will not miss an opportunity to die"! Efforts are now being made to establish significant numbers of young Redwoods in suitable sites. However, survival of the species may eventually depend on the greater vigour of hybrids with the Ebony, from which it may be possible to reconstitute a healthy stock closely resembling the original Redwood. |
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Post by Melanie on Dec 27, 2006 14:28:44 GMT 1
NATURAL HISTORY When the island was first discovered, redwoods were found grorwing in large numbers in the upland areas below the tree fern thicket. Redwoods grew with a straight trunk to give a medium sized tree of about six metres. The Redwood was the most valuable endemic tree to settlers on the Island because it produced a fine hard grain timber and the bark of the tree was used for tanning the hides of cattle. Very quickly nearly all the trees were cutdown or barked, resulting in the redwood nearly becoming extinct as early at 1718. Since 1718, redwoods have remained very rare, only being recorded near Diana's Peak and High Peak. By the twentieth century, redwoods were only found growing in private gardens and a single tree ner High Peak. DESCRIPTION Today the redwood only grows to three metres in height, no longer able to reach heights of six metres due to inbreeding. Some trees still grow with single straight trunk although others are considerable dwarfed and mis-shapen.'The leaves are pale green, older leaves quickly turn yellow and speckled and fall, about 75mm long and 50 to 60 mm wide. The main flowering season is in November but flowers can be produced throughout the year. The flowers are about 75mm long and open up to 50mm in diameter and hang down from the tree. At first they are pure white, turning pink with age so that finally the dying flower is deep red. NUMBER OF SURVIVING POPULATION The redwood is extinct in the wild. This means that there are no longer any natural populations surviving in their native habitat of the Cabbage Tree Woodland. The last tree to survive in the wild which grew below the waterfall at Peak Gut died in the early 1960's. Norman Williams recalls the tree as being about four metres in height with a spreading canopy of four main limbs. A seedling if this tree was planted at Red Rock but this died in 1992. Another seedling was planted at Scotland which died in 1988. This tree was dwarfed because it lacked a strong leader. Seedlings from the old Scotland and Red Rock trees still survive at Scotland, High Peak and Mount Pleasant. All of these seedlings are from self-pollinate and thus are very in-bred. In April 1997 the first ever cross-pollinated redwood seedlings were planted out in a seed orchard within the Diana's Peak National park. These seedlings could mark a recovery in the health of the redwood. If not improvement in the growth of redwoods happens then this could mark the inevitable extinction of the species because its genetic base has been irretrievably weakaned. CONSERVATION RECOVERY PROGRAMME The redwood is the subject of a genetic improvement programme. That is, we are trying to improve the growth and health of the species through cross-pollinations and selecting the fittest seedlings to be part of our recovery work. It is hoped that by selecting only the fittest seedlings and using these as the parents of the next generation of redwoods improvements can be made. The aim is to get to a point when the redwoods are fit enough to be reintroduced in to a wild situation and be able to regenerate naturally. If this cannot be acheived because the genetic base of the species has been destroyed, then the redwood's fate will be like that of the dodo.  |
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Post by anotherspecialist on Jul 6, 2008 11:09:31 GMT 1
Trochetiopsis erythroxylon (Forst.f.) W. Marais St. Helena Redwood The St. Helena Redwood, T. erythroxylon, is a small tree. It used to grow to 6m in height, but due to the adverse effects of inbreeding it now only reaches 3m. The bark is an even dark brown in colour, and relatively smooth in texture. The foliage is alternate, petiolate and stipulate. The stipules are awl-shaped. The ovate leaves are pale green, about 3" long, and 2" or more wide. They are 3–5-nerved, cordate at the base, with crenulate margins, and acuminate at the apex. The upper surface is smooth. The lower surface is reticulate, and hoary when young. Older leaves quickly turn yellow and speckled, before falling. It flowers primarily in late spring, but flowers can be produced at any time of year. They are borne on solitary axillary peduncles, with two or three flowers on each peduncle. The peduncles are about the same length as the leaf petioles. The flowers are trumpet shaped, about 2" across, and 3" long, and are borne pendantly. They open pure white, but age first to pink, and finally to a deep red. The flowers have 5 stamens, and also five flesh-coloured staminodes. The style is about twice the length of the stamens. The fruits are oblong, pointed, hairy, capsules with 3 to 5 seeds in each cell. The calyx is persistent, and in fruit exceeds the capsule in length, The St. Helena Redwood was an emergent in and a major constituent of the Cabbage Tree Woodland zone of the moister upland regions of St. Helena, between the heights of 500m and 650m, above the Gumwood zone, and below the tree palm zone. It was exploited for its wood, which provided a close-grained, mahogany-coloured, hard, durable timber, and its bark (using for tanning cattle hides), and also suffered from the depredations of imported goats, and was very rare by 1718. It is now extinct in the wild; the last wild tree having died in the 1950s. Selfed seedlings of this tree were planted in a number of locations. These trees display the effects on inbreeding depression, often being dwarfed or misshapen. Cross-pollinated seedlings were planted in 1997, and it is hoped that these will show healthier growth. www.malvaceae.info/Genera/Trochetiopsis/Trochetiopsis.html |
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Post by anotherspecialist on Jul 6, 2008 11:09:53 GMT 1
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Post by anotherspecialist on Jul 6, 2008 11:14:41 GMT 1
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Post by anotherspecialist on Jul 6, 2008 11:17:48 GMT 1
 Repository Botanische Staatssammlung München (M) Collection Type specimens Collector Forster, No# 123 Collection date null Locality Africa, Ins. S. Helena, Oc. Atlant. Arbor. Country Unknown (Saint Helena) Identifications Type of Pentapetes erythroxylon G.Forst. [family STERCULIACEAE] (stored under name); Verified by Nicolson, D.H., 2004/3/5 Type of Trochetiopsis erythroxylon (G.Forst.) Marais [family STERCULIACEAE]; Verified by Nicholson, D.H., 2004/3/5 Repository Botanische Staatssammlung München, Munich, Germany, M0109384 Data last modified 2004-12-29 www.aluka.org/action/showMetadata?doi=10.5555%2FAL.AP.SPECIMEN.M0109384 |
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Post by Surroundx on Apr 26, 2015 9:21:44 GMT 1
Cronk, Q. C. B. (1983). The decline of the redwood Trochetiopsis erythroxylon on St Helena. Biological Conservation 26(2): 163-174. [ Abstract] |
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Post by Surroundx on May 8, 2015 17:40:25 GMT 1
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Post by koeiyabe on Jan 10, 2019 1:59:42 GMT 1
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