Australian Families of Flowering Plants Pt 2

Australian Plant Diversity – Context

• Vascular flora totals (2009 ANBG statistics)

  • $\text{Native spp.}\;\approx 20\,000\text{–}21\,000$

  • $\text{Naturalised spp.}\;\approx 3\,000$

  • $\text{Combined native + naturalised}\;\approx 23\,000\text{–}24\,000$

  • $83$ species presumed extinct, $1\,202$ ( $6.4\%$ ) listed as threatened.

  • Endemism very high: $\approx 93.25\%$ of native taxa.

• State-by-state vascular-plant census (1990 data)

  • NSW $5\,930$ spp.; NT $3\,555$; QLD $8\,696$; SA $3\,657$; TAS $2\,197$; VIC $3\,593$; WA $8\,316$.

• Queensland 2013 census (illustrates scale of task for practical exam)

  • Flowering plants: $8\,100$ native | $1\,262$ naturalised.

  • Gymnosperms $70$ ( $64$ native).

  • Ferns & allies $392$ ( $381$ native).

  • Bryophytes $561$; liverworts/hornworts $437$.

• Present structural vegetation (area, % of continent)

  • Tall shrublands (mallee, mulga): $2.39\times10^{6}\,\text{km}^2\;(31.1\%)$ – the single largest unit.

  • Open woodlands (eucalypt/acacia): $1.99\times10^{6}\,\text{km}^2\;(25.8\%)$.

  • Forests (closed + open): $\approx 0.4 + 4.6 = 5\%$ total cover – yet ecologically and economically dominant.

Major Plant Families – Australian vs. World Totals

• Australian “Top 14” (focus families in bold):

  • Myrtaceae $1\,646\,\text{spp.}$

  • Proteaceae $842\,\text{spp.}$

  • Mimosaceae (Mimosoideae) $650\,\text{spp.}$

  • Rutaceae $365\,\text{spp.}$

  • Chenopodiaceae $300\,\text{spp.}$

  • Epacridaceae → Epacridoideae $356\,\text{spp.}$

  • Goodeniaceae 366 spp

  • Lamiaceae $250\,\text{spp.}$

• Largest genera (>$100$ spp.) help in rapid field recognition

  • $Acacia\,(772)\rightarrow\text{Mimosoideae}$ – Australia’s most speciose genus.

  • $Eucalyptus\,(569), Melaleuca\,(176)$ – Myrtaceae.

  • $Grevillea\,(260), Hakea\,(134)$ – Proteaceae, etc.

Family Profiles

7. Myrtaceae – The Eucalypt Family

• Diversity

  • Worldwide $\approx132$ genera / $5\,950$ spp.

  • Australia $\approx70$ genera / $1\,646$ spp. – dominant in sclerophyll forest.

  • Iconic genera: $Eucalyptus\,(\sim700\,spp.), Melaleuca\,(\sim300), Callistemon, Leptospermum, Kunzea, Syzygium.$

  • State emblem: $Eucalyptus\,globulus$ (Tasmania).

• Morphology & anatomy

  • Woody shrubs → tall emergent trees; aromatic leaves packed with oil glands.

  • Flowers: $4$–$5$ sepals + petals; numerous exserted stamens borne on a hypanthium above an inferior ovary.

  • In eucalypts sepals + petals fuse into an operculum (bud cap) that pops off at anthesis.

  • Fruit usually woody capsule (forest spp.) but fleshy in rainforest genera (e.g. $Syzygium$).

• Ecology

  • Dominate non-arid forest & woodland; few spp. extend to New Guinea, Timor, Celebes.

  • Oils confer drought/fire resistance; bark types (stringybark, ironbark, mallee, etc.) diagnostic in field.

• Human uses

  • Ornamentals (Callistemon ‘Bottlebrush’, Melaleuca spp.).

  • Essential oils: tea-tree (Melaleuca alternifolia) & eucalypt oils (cineole, menthol substitutes).

  • Spices: clove – $Syzygium\,aromaticum$; allspice – $Pimenta\,dioica$.

  • Timbers: $E.pilularis$ (blackbutt), $E.marginata$ (jarrah), $E.regnans$ (mountain ash).

• Threats & pathology

  • Myrtle rust $Puccinia\,psidii\,s.l.$ – infects many cultivated species (lilly pilly, willow myrtle, etc.).

• Garden case-studies (local examples, good for ID during prac.)

  • Red Bottlebrush $M.(Callistemon)\,viminalis$ (drooping habit, bird-attracting).

  • Lemon Myrtle $Backhousia\,citriodora$ – bush-food, strong citral aroma.

  • Golden Penda $Xanthostemon\,chrysanthus$ – street tree with fluorescent yellow heads.
    (Catalogue notes give horticultural requirements, flowering times, pollinator links.)

8. Proteaceae – Waratahs, Grevilleas & Banksias

• Gondwanan family: disjunction S Africa ↔ Australia/PNG ↔ South America.

• Diversity: $\approx83$ genera / $1\,660$ spp. globally; Australia $45$ genera / $842$ spp.

• Flagships: $Telopea\,speciosissima$ (NSW floral emblem), $Banksia, Grevillea, Hakea, Macadamia$.

• Diagnostic traits

  • Sclerophyllous shrubs–trees; tough, often serrate leaves.

  • Inflorescences compound – heads or spikes of many small 4-tepaled flowers united into a tube.

  • Each flower: $4$ stamens + single long style with pollen presenter (swollen stigma-region that first serves as pollen donor).

  • Usually woody follicle fruit suitable to post-fire release.

  • Bird (honeyeater) & mammal pollination common; high nectar rewards.

• Human relevance

  • Edible nut: $Macadamia\,integrifolia$ – only major Australian indigenous crop.

  • Cut flowers (waratahs, banksias) & landscape cultivars (dwarf grevilleas).

• Local Banksia examples (recognition in lab)

  • $B.spinulosa$ (Hairpin): orange/yellow spikes, hardy.

  • $B.robur$ (Swamp): needs moist sandy soils.

  • $B.oblongifolia$ (Dwarf): coastal heaths; good for compact gardens.

9. Mimosaceae → Subfamily Mimosoideae – The Wattles

• Systematics & controversy

  • Originally Fabaceae split into $3$ subfamilies (Faboideae, Caesalpinioideae, Mimosoideae).

  • Name row: Acacia genus re-typification (Africa vs Australia). 2005 & 2011 IBC votes retained Australian clade as Acacia; African spp. reassigned (Vachellia, Senegalia, etc.).

• Diversity

  • Global $\approx40$ genera / $2\,500$ spp.

  • Australia $\approx17$ genera; $\sim900$ Acacia spp. (> $1/3$ of world total).

  • National emblem: Golden Wattle $Acacia\,pycnantha$.

• Morphology

  • Seedlings bipinnate; many adults develop phyllodes – flattened petiole/rachis taking over photosynthesis.

  • Flowers in heads or spikes: minute calyx + corolla ( $4$–$5$ parts) hidden by numerous showy stamens (yellow/cream).

  • Legume pod fruit; nitrogen-fixing via rhizobia.

• Ecology/biology

  • Pioneers after fire/clearing – fast growth, early death; enrich soil $N$.

  • Pollination by wind, bees, butterflies.

  • Misconception: wattle pollen ≠ hay-fever culprit; grass/weed pollen is offender.

• Key structures for pracs (Name That Flower diagrams)

  • Pulvinus, glands on rachis, globular vs cylindrical inflorescences, marginal placentation in ovary, etc.

10. Epacridoideae (formerly Epacridaceae) – Southern Heaths

• Systematics: now basal subfamily of Ericaceae.

• Diversity: worldwide $31$ genera / $426$ spp.; Australia $29$ genera / $356$ spp.; high endemism.

• Victorian floral emblem: $Epacris\,impressa$.

• Traits

  • Woody heath shrubs (xeromorphic: small, tough, mucronate leaves; visually ‘parallel’ veins actually palmate, best seen abaxially).

  • Flowers actinomorphic, $5$-merous, sepals grade to bracts.

  • Corolla often tubular; anthers enclosed.

  • Axile placentation in ovary.

• Examples for labs: $Leucopogon, Styphelia, Richea, Astroloma$.

11. Chenopodiaceae – Saltbushes & Glassworts

• Halophytic specialists – dominate saline/arid habitats; scarcely tropical or rainforest.

• Diversity: $\approx100$ genera / $1\,500$ spp. globally; Australia $31$ genera / $300$ spp.

• Economic taxa: $Spinacia\,oleracea$ (spinach); $Beta\,vulgaris$ (beetroot, sugar beet).

• Traits

  • Herbs/shrubs; many stem-succulent & jointed (glassworts).

  • Leaves small & fleshy, lacking stipules; minute bladder hairs collapse → silvery sheen.

  • Flowers tiny, apetalous; calyx $5$-lobed; $5$ stamens; $2$ carpels.

• Australian significance

  • $Atriplex$ fodder during drought; tidal samphires ($Sarcocornia, Suaeda$) important for coastal ecosystems.

12. Goodeniaceae – The Fan-Flower Family

• Southern-hemisphere, mainly Australian radiation: $\approx400$ spp., $10$–$12$ genera; Australia $366$ spp.

• Unique morphological hallmark: indusium – cup atop style that collects anthers’ pollen pre-anthesis and later presents it to pollinators (secondary pollen presentation).

• Floral traits

  • Zygomorphic; corolla lobes often winged (half-wheel/fan appearance).

  • Ovary inferior‐to‐half-inferior; axile placentation.

• Habitat range: almost everywhere except closed rainforest.

• Recognisable genera: $Scaevola$ (coastal fan-flowers), $Goodenia, Lechenaultia, Dampiera$.

• Local horticultural examples (praxis)

  • $Scaevola\,calendulacea$ (Dune fan-flower): sand-binder with year-round blue flowers.

  • $Goodenia\,ovata$ (Hop goodenia): shrub, bright yellow flowers, lizard habitat.

13. Rutaceae – Oranges & Native Fuchsias

• Worldwide $\approx150$ genera / $1\,800$ spp.; Australia $43$ genera / >480 spp.; $95\%$ endemic.

• Subfamilies in Australia – esp. Rutoideae (largest): $Boronia\,(95), Correa$, $Crowea$, $Eriostemon$, $Phebalium$.

• Morphology

  • Woody, strongly aromatic – oil glands visible as dotted translucent spots (rutaceous odour when crushed).

  • Leaves often with stellate hairs/peltate scales.

  • Flowers actinomorphic $4$–$5$-partite; stamens often $2\times$ petal number.

  • Superior ovary; nectar disc common.

• Human relevance

  • Citrus fruits (cultivated exotics & natives). Rapidly growing boutique crop: Finger lime $Citrus\,australasica$ – > $40$ cultivars; grafted onto standard citrus rootstock, used in gastronomy (“citrus caviar”).

  • Ornamentals: $Correa\,reflexa$ (native fuchsia), $Boronia\,megastigma$ (perfume oils).

14. Lamiaceae (Labiatae) – The Mint Family

• Global $\approx200$ genera / $3\,000$ spp.; Australia $\approx40$ genera / $250$ spp.; Mediterranean origin but radiation across open, sunny habitats worldwide.

• Identifying characters

  • Square, often pubescent stems; opposite decussate, aromatic leaves (rich in volatile terpenes).

  • Flowers strongly zygomorphic; bilabiate corolla; $2$ (rarely $4$) didynamous stamens.

  • Fruit typically schizocarp of $4$ nutlets.

• Uses

  • Culinary/insecticidal/medicinal herbs: $Mentha, Salvia, Thymus, Rosmarinus, Lavandula, Origanum, Melissa$.

  • Australian ornamentals: $Prostanthera$ (mint-bushes), $Westringia$ (coastal rosemary), $Coleus/Plectranthus$ (shade herbs).

• Garden examples

  • Endangered $Coleus\,habrophyllus$ – Ipswich/Ormeau, strong aroma.

  • $Prostanthera\,ovalifolia$ – lilac mint-bush; ideal hedge, scented.

Additional Monocot Highlight – Xanthorrhoea (Grass Trees)

• $30$ spp., all endemic.

• Habit: tufted perennial herbs to small arborescent forms; trunk formed by accumulated leaf bases + resin.

• Xeromorphic adaptations; dominate heath & sclerophyll landscapes.

• Cultural/Economic use by First Nations peoples

  • Edible: sweet drink from flower-spike infusion; soft leaf bases.

  • Resin adhesive; flower spike as spear shaft; fibre for net-making.

Learning Objectives – Exam Alignment

• Accurately describe vegetative + reproductive characters of eight focus families.

• Provide at least one local species & two human uses per family.

• Recognise lab-specimen structures: oil glands (Myrtaceae/Rutaceae), phyllodes (Acacia), pollen presenter (Proteaceae), indusium (Goodeniaceae), bladder hairs (Chenopodiaceae), square stems (Lamiaceae).

• Understand ecological roles: nitrogen fixation (Mimosoideae), post-fire seed release (Proteaceae), halophyte succession (Chenopodiaceae).

• Be able to relate families to vegetation types and land-management issues (fire regimes, salinity, invasive pathogens).

Glossary / Key Structures to Label

• Hypanthium, operculum, phyllode, pollen presenter, indusium, schizocarp, follicle, superior vs inferior ovary, axile vs marginal placentation, tepals, bilabiate corolla, stellate hairs, bladder hairs.

Practical Tips

• Carry a hand-lens (×10) to see leaf oil glands, hair types, indusium, etc.

• Smell & crush foliage (safe species only) to link scent with family (Myrtaceae vs Rutaceae vs Lamiaceae).

• In dichotomous keys, stamen number, ovary position, leaf arrangement, hair/gland type are quickest eliminators.

• Re-draw lecture diagrams (Name That Flower plates) labelling floral formulae.

• Review herbarium sheets + living specimens pre-exam; match with numerical family sizes to assess likelihood in a quiz.