Trees of Western Australia

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Journal of the Department of Agriculture, Journal of the Department of Agriculture, Western Australia, Series 3 Western Australia, Series 3

Volume 2

Number 2 March-April, 1953 Article 11

3-1953

Trees of Western Australia - the grey box Trees of Western Australia - the grey box

C A. Gardner

Department of Agriculture

Follow this and additional works at: https://library.dpird.wa.gov.au/journal_agriculture3 Part of the Botany Commons

Recommended Citation Recommended Citation

Gardner, C A. (1953) "Trees of Western Australia - the grey box," Journal of the Department of Agriculture, Western Australia, Series 3: Vol. 2: No. 2, Article 11.

Available at: https://library.dpird.wa.gov.au/journal_agriculture3/vol2/iss2/11

This article is brought to you for free and open access by the Agriculture at Digital Library. It has been accepted for inclusion in Journal of the Department of Agriculture, Western Australia, Series 3 by an authorized administrator of Digital Library. For more information, please contact [email protected].

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By C. A. GARDNER, Government Botanist

No. 16—THE COOLABAH (Eucalyptus microtheca F. Muell) and

No. 17—THE GREY BOX (Eucalyptus tectifica F. Muell)

T

HE coolabah and the grey box are two common tropical trees which closely resemble each other in bark, foliage and other characters, but which differ widely in their soil requirements a n d in their timbers. Both are numbered among the most valuable trees of the Kimberley district because of the strength and durability of their exceedingly h a r d timbers and their resistance to the ravages of the termite.

To those who classify trees accord- ing to their bark characters, both t h e coolabah and the grey box are typical

"box trees", each possessing close, p e r - sistent bark not unlike t h a t of the t u a r t or the trunk of the york gum.

THE COOLABAH (E. microtheca F. Muell)

The coolabah of t h e Kimberleys always has this rough persistent bark except on its smaller branches, al- though even these are occasionally rough-barked. The bark of the larger coolabah trees is often deeply fissured.

On the other hand, in the southern forms of the coolabah, t h e whole of the trunk and branches may be white and smooth. Coolabah trees found in a n area extending from t h e Strelley River as far south as the Murchison River have bark which appears to have been whitewashed, t h a t is to say it has an external m a t t - w h i t e powdery bark which is easily rubbed off.

The white-barked trees of the Mur- chison River were called "callaille" or

"yathoo" by the aborigines.

This form of coolabah is apparently not found outside Western Australia, but in Central Australia, trees with rough bark over all, or the greater part, of the trunk, with smooth branches are not uncommon. The Central Austra- lian tree was formerly named Eucalyp- tus coolabah, a n a m e t h a t h a s fallen into disuse.

The timber of the two West Aus- tralian forms appears to be different.

The northern coolabah has a deep sepia-brown excessively h a r d timber with an interlocked grain traversed by numerous whitish threads. In h a r d - ness it is unsurpassed among Austra- lian eucalyptus timbers, being about as hard as the famed lignum-vitae of t r o - pical America, but lacking the oily character of the latter. Coolabah trees from the Gascoyne and Murchison dis- tricts have a reddish-brown timber t h a t is very hard, heavy and elastic.

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-Coolabah tree (E. microtheca F. Muell) near Fitzroy Crossing, West Kimberley.

In the Kimberleys the coolabah tree attains a diameter of up to four feet. The timber is used for buildings (especially for posts in the soil) and for stock yards. No visitor to the Kim- berleys can fail to be impressed by the amount of labour expended on the con- struction of these massive post-and-rail stock yard fences which are six to eight feet in height and of extraordinary strength and solidity.

The coolabah tree in both of the forms has its own particular habitat.

It is found exclusively near rivers and water courses on alluvial soils subject to periodic inundation and it appears to favour a clay subsoil. Extensive areas of this nature occur throughout the length of the Fitzroy river to the south of the Geickie Gorge and along the plains of its principle tributaries, the Margaret, Mary and Louisa Rivers, and Christmas Creek. It is also common along the Lennard river and lower Ord river, but much less common on the streams of the Hann plateau to the north of the King Leopold Range.

Fig. 2.—Large coolabah, showing deeply-Assured bark.

BOTANICAL DESCRIPTION

COOLABAH (Eucalyptus microtheca F. Muell.)—

A tree attaining a height of over 80 feet, but more frequently 40-60 feet tall, with widely spreading branches, more richly branched than most tropical Eucalyptus trees, the crown as broad as the tree is tall; the trunk relatively short, up to four feet in diameter, and together with the main branches covered with a grey hard fibrous-flaky, usually deeply-fissured bark, brown in fracture, the bark of the upper branches and branchlets usually smooth, but the smooth bark sometimes extending down the branches, or the entire bark smooth, matt- white, and appearing whitewashed; the timber deep sepia-brown in colour, very hard and dense with an interlocked grain. Branchlets slightly angular.

Leaves alternate, stalked, lanceolate to oblong, acute or more frequently obtuse, straight or sickle- shaped, 6-15 cm. long, the same colour on both surfaces, dull, leathery, the midrib prominent, the lateral nerves widely diverging from the midrib and loosely anastomosing, forming an open network, the intramarginal nerve distant from the leaf-margin.

Umbels 3-7-flowered, arranged in small terminal or axillary panicles, the peduncles and pedicels short.

the pedicels usually shorter than the calyx-tube.

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Calyx-tube almost hemispherical, 3-4 mm. long or more, smooth; operculum (cap) hemispherical, obtuse or umbonate, smooth, varying from slightly shorter, to slightly longer than the calyx-tube.

Stamens in a continuous ring, all perfect, the filaments inflected in the bud, yellowish-white in colour; anthers baslflxed, ovoid to almost globular, opening longitundinally in short broad silts which almost converge upwards, but remain quite distinct.

Fruit variable in shape from hemispherical to cup- shaped, rather thin, falling after the seeds have matured, or perhaps before, 3-5 mm. long and about as broad, often slightly contracted at the top, the rim thin, the disc lining the calyx-tube. Capsule more than half free, 3-4-locular, the broadly ovate valves flush with the rim or slightly protruding.

Fertile seeds elliptical; cotyledons broadly cordate- reniform. Flowering season, January-February.

Fig. 3.—The grey box {E. tectifica F. Muell).

Photo: R. A. Perry.

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THE GREY BOX (E. tectifica F. Muell)

In the grey box the rough bark ex- tends to the ultimate branches, unlike that of the coolabah where the smaller branches are usually smooth.

The grey box is the common tree of the basalt areas to the north of tne

King Leopold Range, but unlike the coolabah it is not found along the streams but is more typical of the stony h i l l s and undulating country. Its occurrence is so closely connected there with basalt and andesite, that this particular soil t y p e can at once be mapped by reference to the grey box trees.

To the south and to the east of the Hann Plateau however, it is found in quite different soils but does not appear to be common in these areas. Apart from isolated specimens I have only found the tree on the sandstone soils at Carlton Hill Station, the high sandy ground along the Fitzroy River between Fitzroy Crossing and Ellen- dale, and the red sandy country close to Yeeda and on the plains of the Len- nard and Barker Rivers between the King Leopold Range and the Lennard River.

Its value as timber is second only to that of the coolabah but it rarely attains a height in excess of 45 ft., with a comparatively slender trunk. The accom- panying photograph shows a small tree. Unlike that of the coolabah, the grey box timber is a deep red in colour and lacks the white threads so characteristic

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COOLABAH (E. microtheca P. Muell) A-H). A—Twigs with buds, flowers and fruits; B—Flower buds (much enlarged); C—Ant«3r; D and E—Fruits (much enlarged); F—Fruit in section; G—Seeds (much enlarged);

H—Coty ledons.

GREY BOX (E tectiflca F. Muell) (I-Q). I—Branchlet wl'h young buds: K—Panicle with bur's (much enlarged)- L—Anther (much enlarged); M and N—Fruits (enlarged); O—Fruit In section; P—Seeds (much

enlarged); Q—Cotyledons. Icon, origin.

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of coolabah. The grey box is stated to be a valuable nectar-producing species.

No information is available con- cerning the oils of the two trees but from field observations it is doubtful whether they have any value in this respect. The young leaves of the grey box have a pleasant odour, suggesting the presence of limonene, but this re- quires confirmation.

Both trees have fruits which fall during the same season as flowering, but they do not persist like those of the southern Eucalyptus species. Those of the grey box are fragile and of a thin almost eggshell-like consistence, being easily crushed between the fingers. In this, the tree resembles the cabbage gum, ghost gum, carbeen and some other tropical species.

The fruit of the coolabah is much smaller and less fragile but equally de- ciduous.

BOTANICAL DESCRIPTION

GREY BOX {Eucalyptus tectifica F . Muell.)—A tree a t t a i n i n g a h e i g h t of 40 l e e t , b u t u s u - u y 20-30 feet tall, w i t h a p r o p o r t i o n a t e l y longer a n d m o r e slender t r u n K t h a n t h a t of t n e coolaDah, a n d rarely exceeding 18 i n c h e s in d i a m e t e r , t h e b r a n c h e s r e m a i n i n g erect a n d relatively few, t h e crown o p e n . Bark p e r s i s t e n t t h r o u g h o u t , pale grey, fibrous-flaky and narrowly fissured, h a r d , d e e p b r o w n i n f r a c - t u r e ; t i m b e r deep red, h a r d a n d d e n s e . B r a n c h l e t s s u b t e r e t e .

Leaves a l t e r n a t e , stalked, l a n c e o l a t e to o b l o n g - l a n c e s l a t e , t h e s a m e colour on b o t h surfaces, dull green or glaucous, l e a t h e r y , u s u a l l y p e n d u l o u s , 8-17 cm. long, a c u t e or a c u m i n a t e , t h e m i d r i b a l o n e p r o m i n e n t , t h e l a t e r a l nerves less widely d i v e r g e n t t h a n in t h e coolabah, a n d u s u a l l y m o r e n u m e r o u s , not close, loosely a n a s t o m o s i n g , t h e i n t r a m a r g i n a l nerve usually r a t h e r close to t h e m a r g i n , except in broad leaves.

Umbels 3-5-flowered, i n t e r m i n a l panicles, or rarely t h e p a n i c l e axillary, s h o r t e r t h a n t h e leaves, t h e p e d u n c l e s r a t h e r slender, t h e pedicels s h o r t . Calyx-tube p y r i f o r m - c a m p a n u l a t e , s m o o t h , m o r e or less t a p e r i n g i n t o t h e s h o r t pedicel, 4-5 m m . long.

O p e r c u l u m h e m i s p h e r i c a l , a p i c u l a t e or u m b o n a t e . n o t broader t h a n t h e c a l y x - t u b e a n d s h o r t e r t h a n it, rarely t h e o p e r c u l u m a l m o s t conical. S t a m e n s all perfect, i n a c o n t i n u o u s series, t h e filaments white, inflected in t h e b u d ; a n t h e r s basifixed, globular-reniform, o p e n i n g i n a l m o s t t r a n s v e r s e slits which almost converge a t t h e top, t h e gland t e r m i n a l .

F r u i t pedicellate, c u p u l a r to c u p u l a r - c y l i n d r l c a l , usually slightly contracted a t t h e orifice, 4-8 m m . long, t h i n a n d fragile, a n d falling after t h e seeds m a t u r e , t h e rim very t h i n , t h e capsule m o r e t h a n half free, 3-4-locu!-ar, t h e valves broad a n d o b t u s e a n d almost flush with t h e rim, or m o r e deeply i n - cluded. Seeds spherical; cotyledons c o r d a t e - r e n i f o r m .

Fig. 4.—Trunk of grey box, showing typical b a r k g r o w t h .

P h o t o : R. A. Perry.

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