Basic
Harden, G.J. & J.B. Williams How to identify plants. UNE, 1984 (41 pp.). [Good intro to use of keys, features of major families, etc.]
Clarke, I. & H. Lee Name that flower. Melbourne University Press, 1993 (260 pp.). This retails for around $30 and provides an easy introduction to understanding the parts of the plant, the necessary terminology, and for many native plants may allow identification to family or genus level. It is not however for identification to species, but a "how to" book.
Bell, A.D. Plant form. Oxford University Press, 1991. (341 pp.). This gives a very clear idea of structure, especially for less familiar or more complicatedsituations (grasses, daisies, etc).
Jeffrey, C. An introduction to plant taxonomy. J.A. Churchill Ltd., London, 1968. [Still a good intro to "alpha" or "classical" taxonomic techniques, but lacks more modern methods and analytical approaches.]
Debenham, C. The Language of botany. Soc. for Growing Austral. Pl., Sydney, 1981. [Useful basic guide to vascular plant terminology.]
Baines, A. (An etymological dictionary of) Australian plant genera. Soc. for Growing Austral. Pl., Sydney, 1981. (406 pp.) [Short profiles of each genus, incl. pronunciation of the name, date genus was described, derivation of name, number of species, habitat, habit, uses, distribution, and further references. Now rather dated, but can be useful.]
Blackmore, S. & E. Toothill (eds). The Penguin dictionary of botany. Allen Lane, 1984. (390 pp.) [Good reference for definitions of botanical terminology.]
Lincoln, R.J., G.A. Boxshall & P.F. Clark A dictionary of ecology, evolution and systematics. Cambridge Univ. Press, 1985. (298 pp.).
Lumley, P. & R. Spencer Plant Names - a guide to botanical nomenclature 2nd edn. Ornamental Plants series, no. 2, Royal Botanic Gardens, melbourne, 1991 (53 pp.). [Excellent readable guide to the principles behind scientific names, with many examples. Deals with both wild species and cultivated plants, the Codes of Nomenclature that apply to each, and a useful section on using scientific names in written and spoken form.]
Sharr, F.A. Western Australian plant names and their meanings - a glossary. Univ. W.A. Press, 1978 (228 pp.) [Short outline of botanical Latin and Greek, and a glossary of terms, then the names; genus and species epithets are treated separately. Useful outside WA, as many genera occur elsewhere and the epithets are used in other genera.]
More Specialized
Chapman, A.D. Australian Plant Name Index (4 vols). Australian Biological resources Study, Canberra; AGPS, 1991. [Comprehensive listing of all scientific names that have been applied to plants occurring in Australia, whether native or naturalized, together with the relevant authors, literature and type citations, and nomenclatural comments. APNI is being continually updated by the National Botanic Gardens in Canberra, and computer updates are available.]
Stafleu, F.A. & R.S. Cowan Taxonomic Literature 7 vols. Bohn, Scheltema & Holkema, Utrecht, 1983-. [Huge amount of info on prominent botanists and their main (non-journal) works; much biographical, bibliographical, and typological information. LIBRARY ONLY.]
Lawrence, G.H.M. et al. (eds) Botanico-Periodicum Huntianum Hunt Botanical Library, Pittsburgh, 1968. [Listing of botanical and related journals and periodicals, with standard and non-standard abbreviations, publication dates, etc. LIBRARY ONLY.]
International Code of Botanical Nomenclature Bohn, Scheltema & Holkema, Utrecht. [Republished every six years or so, following amendments to the Code at each International Botanical Congress. LIBRARY ONLY.]
Stuessy, T.F. Plant taxonomy - the systematic evaluation of comparative data. Columbia Univ. Press, 1990. (514 pp.). [Useful, thorough, and readable text on sources of data, philosophical and methodological options in taxonomy, and species concepts.]
Willis, J.C. A dictionary of the flowering plants & ferns, 8th edn. (revised by H.K. Airy Shaw). Cambridge Uni Press 1973. [Near-comprehensive listing of family and generic names with information on family assignment, authors, synonymy at genus and above, some diagnostic info, etc. Still useful for checking spellings and authors, and snippets of other information, but now substantially dated, and replaced by works (q.v.) by Mabberley, Brummitt, and Gunn et al.]
Brummitt, R.K. Vascular plant families and genera. Royal Bot. Gardens, Kew, U.K., 1992. ["A listing of the genera of vascular plants of the world according to their families, as recognised in the Kew Herbarium, with an analysis of relationships of the flowering plant families according to eight systems of classification." Very up-to-date; gives a comprehensive alphabetical list of genus names, indicating which are recognised and which are synonyms, with authors and what family they belong to. This is complemented by a separate list of families and their constituent genera, and where the family is placed in various higher-order classifications. A few errors and omissions; the Australian genus Rhytidosporum (Pittosporaceae) is missing from both lists; Hippobroma, Isotoma, Laurentia, Lobelia are accidentally omitted from the genera listed under Campanulaceae. See also Gunn et al. for a similar American-based work.]
Gunn, C.R. et al. Families and genera of spermatophytes recognized by the [U.S.] Agricultural Research Service. U.S. Dept of Agric., Technical Bull. No 1796, 1992. [Rather similar to Brummitt (above), but with a less comparison of classification and more citational information. Comprises three catalogues. A family catalogue lists recognised family names, with past synonyms. A family/genus catalogue lists recognised and synonymized genera under the relevant family; literature references are given for synonymization events. A genus catalogue lists genera alphabetically, and indicates the family to which they belong.]
Mabberley, D.J. The Plant Book - a portable dictionary of the higher plants. Cambridge Uni Press, 1987. [An updated but abridged version of Willis/Airy Shaw's book.]
Stearn, W.T. Botanical Latin. Nelson, 1966, 1973?. [The most widely used compilation on botanical Latin (and Greek). Includes vocabulary lists, guides to construction of Latin diagnoses, etc. Useful for stumbling through Latin descriptions, and for translating plant names and technical terminology.]