Thuya 183 



Thujopsis, which were united with it by Bentham and Hooker. So limited, it 

 comprises 5 species, and is divided into the two following sections : 



I. Etithuya. Cones with thin, coriaceous mucronulate scales, those of the 2 or 

 3 middle ranks being fertile. Seed thin, with lateral wings and a minute hilum. 

 This section comprises 4 species. Thuya occidentalis and Thuya plicata of North 

 America, Thuya sutchuenensis of central China, and Thuya japonica of Japan. 



II. Biota. Cones with thickened, conspicuously umbonate scales, which are 

 fleshy when young, almost ligneous when ripe ; those of the lowest two ranks 

 fertile. Seed thick, without wings, the hilum being large and oblong. This 

 section includes one species, Thtiya orientalis of north China. 



The Thuyas resemble considerably in foliage and habit the flat-leaved cypresses. 

 The latter are best distinguished by their fruit, which consists of peltate scales fitting 

 closely by their edges. In a subsequent part, the peculiarities, as regards the branch 

 systems and leaves, of these cypresses {Cupressus Lawsoniana, nootkatensis, thyoides, 

 obtusa, and pisifera) will be described, and may then be compared with those now 

 given below for the four species of Thuya in cultivation. 



In the discrimination of the Thuyas, in addition to the characters shown by the 

 bark, mode of branching, and fruit, the primary and secondary axes of the branch- 

 systems give good marks of distinction. These axes are markedly flattened in Thuya 

 occidentalis, terete in the other species. In Thuya orientalis the branch-systems 

 stand in vertical planes, the inner edges of which are directed towards the stem of 

 the tree. In ordinary forms of the other three species they are arranged in 

 horizontal planes. The leaves on the main axes in each species differ as follows : 



1. Thuya plicata:^ widely spaced, long, ending in long, fine, free points, which 

 are parallel to the axis ; glands inconspicuous or absent. Under surface of the 

 foliage usually marked with white streaks. 



2. Thuya japonica : placed closely together, shoots ending in short, rigid, thick, 

 triangular points, directed outwards at an acute angle ; glands absent. Under 

 surface of the foliage conspicuously marked with broad white streaks. 



3. Thuya occidentalis : widely spaced, ending in long, fine points, which are 

 parallel to the axis ; glands raised, large and conspicuous on the flat leaves. Under 

 surface of the foliage pale green ; white streaks inconspicuous or absent. 



4. Thuya orientalis : widely spaced, ending in short triangular free points, 

 which are not rigid, and are directed slightly outwards at an acute angle : flat leaves 

 marked by longitudinal glandular depressions. Under surface of the foliage pale 

 green, without white streaks. 



Thuya sutchuenensis, Franchet,^ is a small tree occurring in north-east Szechuan 

 in central China, where it was discovered by Pere Farges growing at an altitude of 

 1400 feet. The branchlets are much flattened, thin in texture, and practically gland- 

 less. Cones composed of 8 obovate scales, the apices of which are slightly thickened. 

 This species has not been introduced into cultivation. 



This species exhales a peculiar aromatic odour, which is different from that of the other Thuyas. 

 2 /our. de Bot. 1899, p. 262. See also Masters in Jour. Linn. Soc. (Bot.) xxvi. 540. 



