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Eucalyptus aequioperta Brooker & Hopper, Nuytsia 9: 58-9 (1993).
T: 3.5 km E of Mt Walker, 20 March 1985, 32°
04'S 118°
47'E, M.I.H.Brooker 8891; holo: PERTH; iso: CANB, MEL, NSW.
Tree or mallee to 10 m tall. Forming a lignotuber.
Bark rough, dark grey, fairly firm and scaly or flaky to fibrous
for about half of to all of trunk and large limbs to ca 15 cm diameter,
becoming slightly tessellated on older trees, smooth above, dull pinkish
grey to whitish.
Branchlets with small oil glands in the pith.
Juvenile growth (coppice or field seedlings to 50 cm):
stems rounded in cross-section, slightly glaucous; juvenile leaves
always petiolate, opposite at lowest nodes but soon alternate, ovate
to elliptic to lanceolate, 2-9 cm long, 0.8-2.5 cm wide, bluish to
glaucous, becoming glossy, green as a sapling.
Adult leaves alternate, petioles 0.8-1.7 cm long; blade linear
to narrowly lanceolate or falcate, 6-11 cm long, 0.6-1.2 cm wide,
base tapering to petiole, margin entire, apex pointed, concolorous,
glossy, green, side veins at an acute or wider angle to midrib, reticulation
moderate to dense, intramarginal vein close to margin, oil glands
mostly intersectional.
Inflorescences axillary unbranched, peduncles 0.5-1.5 cm long;
buds 9 to 15, pedicellate, ovoid with operculum equal to or narrower
than hypanthium at the join, scar present, operculum bluntly to acutely
conical, stamens inflexed, anthers oblong, versatile, dorsifixed,
dehiscing by longitudinal slits, style stout, long and straight, stigma
blunt to slightly rounded, locules 3(4), the placentae each with 4
vertical rows of ovules; flowers white.
Fruit pedicellate, shortly barrel-shaped to obconical tending
to truncate-globose, 0.4-0.6 cm wide, disc descending vertically,
valves 3(4), near rim level.
Seed mid-brown, 0.8-1.5 mm long, flattened ovoid, dorsal surface
shallowly and clearly reticulate, hilum ventral.
Cultivated seedling (measured at ca node 10): cotyledons reniform;
stems rounded in cross-section; leaves always petiolate, opposite
for 3 to 8 nodes then alternate, ovate to lanceolate 4.5-10 cm long,
1.3-3.5 cm wide, dull, concolorous, green.
NOTES
Eucalyptus aequioperta (Latin, aequiopertus,
equal cover, referring to the similarity of the operculum with the
hypanthium).
A rough-barked tree or mallee endemic to Western Australia occurring
in the wheatbelt and goldfields in the area bounded by Corrigin, Southern
Cross, Forrestania Cross-roads and Coolgardie, but its distribution
is not well known and may extend as far east as Lake Minigwal.
Eucalyptus aequioperta belongs in Eucalyptus sub-genus
Symphyomyrtus section Dumaria because the buds have
two opercula, stamens are strongly inflexed, ovules are in 4 rows
on the placentae and cotyledons are reniform. Within section Dumaria
it belongs to a small sub-group of 9 closely related species which
are together called series Ovulares. The series is further
diagnosed by glandular pith, cuboid anthers, and seeds with a brown
shallowly and clearly reticulate dorsal seed coat.
Some of the species in series Ovulares are completely smooth-barked
(E. cyclostoma , E. cylindrocarpa , E. exigua
and smaller plants of E. oraria ) and therefore easily distinguished,
while others (E. aequioperta, E. baudiniana , E.
brachycorys , E. myriadena and E. ovularis ) have
rough bark over at least part of the stems. E. aequioperta
has small ovoid buds which in some populations are "egg-in-eggcup"-like.
Its nearest relative geographically and morphologically is E. ovularis
which has buds distinctly widest at the base, and a more southerly
distribution between Norseman and Grass Patch and eastwards towards
Mt Ragged. E. myriadena differs by having more cylindrical
buds and more extensive rough bark than E. aequioperta.
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