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A deciduous tree attaining the same size as the common oak, Q. robur, and not differing in its bark; it differs in its habit, having straighter branches and a trunk that usually penetrates further into the crown than is the case with the common oak; buds usually rather more elongated and acute at the apex. Leaves broadest at or only slightly above the middle, hence not so markedly obovate or oblanceolate as in Q. robur and less tapered to the base, which is cuneate or cordate and lacks the auricles characteristic of the common oak; the texture is usually somewhat firmer, the upper surface rather more glossy, and the underside has persistent hairs on the midrib and main veins and sometimes scattered stellate hairs on the surface of the blade; intercalary veins, i.e., veins running out to the sinuses between the lobes, are much less frequent than in Q. robur, and the lobing is more regular; the stalk, very short in the common oak, is 3⁄8 to 11⁄4 in. long in the durmast oak. Female flowers with almost sessile stigmas (styles usually well developed in Q. robur). The common name ‘sessile oak’ refers to the fruits, which are borne directly on the twig and not on a long slender peduncle as in Q. robur. The scales of the acorn-cup are rather more numerous and more closely imbricated than in Q. robur.
The general distribution of Q. petraea is similar to that of Q. robur, with the notable difference that it does not extend so far to the east on the Continent. In the British Isles the durmast oak avoids the heavy clay soils of the Weald and the Midland Plain but is the commoner species on siliceous soils in the north and west, and is also to be found on light, non-calcareous soils in southern England, often in association with the common oak.
The fine tree at Whitfield, Herefordshire, mentioned in previous editions, still exists and measures 135 × 141⁄4 ft (1963). Others measured recently are: Oakley Park, Shrops., 111 × 221⁄4 ft and 85 × 231⁄4 ft (1971); Nettlecombe, Som., 112 × 213⁄4 ft and 95 × 23 ft (1959); Shobdon, Heref., about 90 × 30 ft (1973); Croft Castle, Heref., 50 × 261⁄2 ft (1960); Knole Park, Kent, 130 × 171⁄2 ft (1969).
On the Continent, the durmast oak comes into leaf and flowers up to two weeks later than the common oak and hybrids between them are therefore by no means common. It is said, however, that in the British Isles there is less difference in flowering time and that hybrids are commoner in consequence. However, both species are variable and minor deviations from the norm are sometimes wrongly taken to be the result of hybridity. For example, the fruits in the durmast oak are sometimes borne on peduncles, but in such cases the peduncle is thick at the base, where it resembles a normal twig. True hybrids, for which the correct name is Q. × rosacea Bechstein, would show such combinations as auricled leaves, downy beneath, on stalks of intermediate length; or peduncu late acorns, leaves almost glabrous beneath but not auricu-late, etc.
The durmast oak has not been so prolific of varieties as Q. robur, but most of the following are or have been in cultivation at Kew:
specimens: Knole Park, Kent, 118 × 191⁄4 ft (1984); Lullingstone Park, Kent, 82 × 291⁄4 ft at 4 ft (1982); Cowdray Park, Sussex, near Polo Lawn, 105 × 25 ft, 92 × 243⁄4 ft and 98 × 221⁄2 ft (1982-4); Mickleham, Surrey, Sandwith Lane, 100 × 20 ft (1984); Woburn Abbey, Beds., Pleasure Gardens, 80 × 22 ft (1977); Tottenham House, Wilts., Savernake Forest, 100 × 191⁄4 ft (1977); Whitfield, Heref., a fine tree mentioned in earlier editions of this work and by Elwes and Henry, 141 × 151⁄4 ft and another two 111 × 181⁄2 ft and 105 × 151⁄4 ft (1984); Easthampton Farm, Shobdon, Heref., an exceptionally fine tree, 82 × 321⁄4 ft (1985); Brockhampton Park, Heref., 95 × 23 ft (1978); Croft Castle, Heref., 115 × 243⁄4 ft and 65 × 271⁄2 ft at 3 ft (1984); Nettlecombe, Som., 80 × 211⁄2 ft and 118 × 24 ft (1984); Oakley Park, Shrops., 111 × 221⁄4 ft and 85 × 231⁄4 ft (1971); Powis Castle, Powys, called ‘The Giant’, 70 × 351⁄4 ft (1984); Munches, Kirkcud., 121 × 191⁄4 ft (1985); Drumlanrig Castle, Dumfr., 105 × 211⁄4 ft (1984).
cv. ‘Columna’. – Although usually listed under Q. petraea, this is probably a hybrid between Q. petraea ‘Muscaviensis’ and Q. robur f. fastigiata.
f. mespilifolia – There are two examples of this interesting variant at Kew, in oak planting west of Broad Walk, 69 × 71⁄4 ft (1973) and in Oak Collection, pl. 1871, 75 × 61⁄2 ft (1978); and another of 80 × 93⁄4 ft in the University Botanic Garden, Leicester (1985).
Q. × rosacea – Mentioned on page 500, this hybrid between Q. petraea and Q. robur is represented by a specimen of 70 × 41⁄4 ft in the Edinburgh Botanic Garden (1985). Natural occurrences of the cross are studied by B. S. Rushton in Watsonia, Vol. 12, pp. 81-101, 209-24 and 315-24 (1978).
Q. lanuginosa subsp. dalechampii (Ten.) Camus
Q. robur subsp. sessiliflora var. tenorei A. DC