A tall evergreen tree of elegant habit and densely twiggy; final subdivisions of the branches very slender and about 1⁄32 in. in diameter. Leaves in the adult state closely appressed to the branches (free at the tips in young specimens) rather glaucous, about 1⁄20 in. long, the exposed part diamond-shaped with a gland in the centre. Cones globose, 3⁄4 to 1 in. wide before opening; scales about six, each 1⁄2 in. wide, with a small boss in the centre; seeds reddish brown. Bot. Mag., t. 9049.
Native of Yunnan, China; originally discovered by Delavay, the French missionary, subsequently by Monseigneur Ducloux, after whom it is named. It was originally introduced by Maurice de Vilmorin about 1905. It was at that time (following Franchet’s identification) regarded as a Chinese form of C. sempervirens. It is closely related to that species but its twigs are more slender, the leaves smaller and more pointed, the cones smaller and with fewer scales, the seeds smaller and scarcely winged.
This species is rare in cultivation and the best specimens known are all in Eire. These are at Kilmacurragh and Mount Usher in Co. Wicklow and at Headfort in Co. Meath, and are between 30 and 40 ft in height. It is tender, when young at least and, in spite of several attempts, has never become established in the National Pinetum at Bedgebury.
From the Supplement (Vol. V)
This species also occurs in south-east Tibet, where specimens were collected by Ludlow, Sherriff and Elliot in an area some way to the east of the type-locality of C. gigantea (see below).
The following recently described species are near to C. duclouxiana:
C. chengiana Hu C. fallax Franco – This differs from C. duclouxiana in the less slender final subdivisions of the branchlets, and the more glandular and wider leaves. A native of western China, described in 1964 and introduced to Britain in 1981. Wilson had found this cypress in the type-area early this century, but the specimens were wrongly identified as C. torulosa in Plantae Wilsonianae.
C. gigantea Cheng & Fu C. fallax Franco, in part; C. chengiana auct., in part, not Hu – A tree attaining a height of 140 ft in the wild. Branchlets fairly stout, closely set. Leaves grey-green, rhomboidal, mostly acute, each with a conspicuous gland on the back. Cones slightly smaller than in C. duclouxiana, with eight to twelve scales.
C. gigantea was described in 1975 from a specimen collected on the Tsangpo river in south-east Tibet. It had, however, been found in this area in 1947 by Ludlow, Sherriff and Elliot (13345), and the specimen they collected was cited by Franco when describing his C. fallax, which thus included both the present species and C. chengiana, though the type belongs to the latter.
C. gigantea was introduced under the field-number cited above, and plants were raised in the University of Washington Arboretum, Seattle. So far as is known, all the plants in this country are young ones, propagated from those at Seattle.