Eucalyptus macarthurii Camden woolly butt

Finely fibrous box-type bark, reaching to high branches, marks this tree as different from most campus trees. The biconical buds are relatively small with slightly exserted valves. Buds and fruit resemble those of the closely related E. bridgesiana. The leaves are rather narrow, up to about ⅝ inch, and have a short terminal bristle. This species is placed in the seemingly heterogeneous Series Viminales, Fl. Australia, 19:344 (1988), including other campus eucalypts E. viminalis, the type, E. bridgesiana, E. globulus, E. gunnii, E. cinera, and E. pulverulenta. Fl. Australia, 19:#420, Page 357; illus. Fig. 96E–F.

The single tree remaining on Crothers Way, close to the Hoover Memorial Building listed as E. macarthurii in the book, appears to be E. melliodora. While Camden wooly butt was historically known from this location, many trees have been lost due to utility work and road access and building improvements and the service access between Hoover and Green Library has largely been replanted in E. sideroxylon. Dr. Matt Ritter, Cal Poly Plant Conservatory Director, wrote in email on 18 December 2005:

The tree appears not to be E. macarthurii for a number or reasons. 1. macarthurii is in the subgenus symphyomyrtus which has outer operculum scars (the outer operculum is shed early in bud development) the tree we looked at had no operculum scars. 2. some of the stamens on the tree we looked at are infertile (staminodes), macarthurii has stamens which are all fertile 3. macarthurii has bark that is rough and persistent over most of the trunk, the tree we looked at has shedding smooth bark over most of the trunk 4. macarthurii has sessile buds, the tree in question has buds on slender, relatively long pedicels. The specimen matches E. melliodora in many traits, specially the deciduous black staminophore on the fruit, and I believe this is the correct identification of this tree.

Related material: Eucalyptus checklist.