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Eucalyptus alligatrix subsp. alligatrix



Eucalyptus alligatrix L.A.S.Johnson & K.D.Hill, Austral. Syst. Bot. 8: 509 (1995) subsp. alligatrix.

T: Victoria: Big River, near junction with Taponga River, SW of Jamieson, 24 Apr. 1973, L.A.S.Johnson 7675; holo:NSW.

Tree to 15 m tall, rarely multi-stemmed from base. Forming a lignotuber.
Bark rough to small branches or rarely the branches <8cm diam. smooth, rough bark thick, fibrous, coarsely furrowed down trunk, dark grey; branchlets glaucous or non-glaucous.
Juvenile growth (coppice or field seedlings to 50 cm):stem rounded or square in cross-section, glaucous or not glaucous, warty or smooth; juvenile leaves always opposite, sessile, orbicular or broadly ovate, 2-4.5 cm long, 2.5-5.2 cm wide, margin entire or crenulate, blue-green, grey-green or glaucous.
Crown composed of opposite, petiolate intermediate leaves and alternate adult leaves.
Adult leaves petiole 0.6-2.4 cm long; blade lanceolate to falcate, 5.4-20 cm long, 1-4.7 cm wide, base tapering to petiole, margin entire, concolorous, glossy or dull, green, blue-green or grey-green,
side-veins greater than 45° to midrib, moderately to densely reticulate, intramarginal vein parallel to and just within margin or well removed from it, oil glands numerous, mostly island.
Inflorescences axillary single, peduncles 0.3-0.7 cm long; buds 3, pedicellate or sessile, ovoid to diamond-shaped, green or glaucous, scar present, operculum conical, stamens inflexed, anthers cuboid or cuneate, versatile, dorsifixed, dehiscing by longitudinal slits (non-confluent), style long, locules 3 or 4, the placentae each with 4 vertical ovule rows; flowers white.
Fruit sessile or shortly pedicellate, cup-shaped, obconical or campanulate, 0.4-0.8 cm wide, sometimes glaucous, disc raised or level, valves 3 or 4, strongly exserted or near rim level.
Seed dark brown, 1-2.2 mm long, ovoid or flattened-ovoid, D-shaped or pointed at one end, usually lacunose, dorsal surface smooth or shallowly pitted, hilum ventral.

Cultivated seedlings (measured at ca node 10): cotyledons bilobed to oblong; stems rounded or squared in cross-section, glaucous; leaves sessile and opposite for many nodes, orbicular to cordate, 2.5-4.5 cm long, 2.2-6.5 cm wide, base amplexicaul to rounded, apex emarginate, rounded or pointed, glaucous to grey-green.


NOTES

Eucalyptus alligatrix ( Latin alligatrix, she who binds together, refers to the relationship of the species to E. cinerea and E. cephalocarpa ).

A small to medium-sized tree of undulating to montane south-eastern Australia inland from the Great Dividing Range.

E. alligatrix
has extensive, thick rough fibrous bark, glaucous juvenile leaves and a crown of adult and intermediate leaves.

It has three subspecies differing in geography and proportion of adult and sub-adult leaves in the crown:

subsp. alligatrix
From the Eildon - Jamieson - Big River area of Victoria with buds in 3s and crown a mixture of alternate narrow adult and opposite broader intermediate leaves.

subsp. limaensis (after the farming district, Lima, in north-east Victoria, where the subspecies occurrs).
Occurs further north than subsp. alligatrix, only near Swanpool in Victoria. A taller tree with a completely adult crown of consistently alternate narrow leaves, buds in 3s and the smallest fruit of the three subspecies.

subsp. miscella (Latin miscella, mixed, refers to the 3 and 7-flowered inflorescences on the same tree).
Has a very restricted distribution near Rylstone, New South Wales, and is a smaller spreading woodland tree with a completely adult crown but with broader leaves than subsp. limaensis. Buds clusters are a mixture of 3s and 7s on the same tree.

Eucalyptus alligatrix belongs in Eucalyptus subgenus Symphyomyrtus section Maidenaria, a large group of species more or less restricted to south-eastern Australia, characterized by bilobed cotyledons, simple axillary inflorescences, buds with two opercula, stamens with versatile anthers and flattened seeds with a ventral hilum. Within this section, E. alligatrix belongs in series Argyrophyllae having longitudinally furrowed fibrous rough bark throughout, orbicular or ovate juvenile leaves opposite for many nodes and small diamond-shaped buds in 3s or mixed 3s and 7s. E. alligatrix has a greener, more adult-leaved crown than E. cinerea and E. conspicua whilst E. cephalocarpa and E. nova-anglica have buds in 7s. These 5 species form series Argyrophyllae.