Plants that live on the exposed frontal dunes have to be salt tolerant and they generally hug the ground as a reaction to the incessant winds. The dominant plant is the grey, creeping grass (Spinifex hirsutus). Other creepers include the guinea flower (Hibbertia scandens) with showy bright yellow flowers; goat’s foot (Ipomoea pescaprae) with mauve flowers; and pigface (Carpobrotus glaucescens) with purple daisy-like flowers. The Pandanus or screw-pine (Pandanus pedunculatus) and coast she-oak (Casuarina equisetifolia) grow on some exposed dunes and at Point Lookout. The coast banksia (Banksia integrifolia) grows in some exposed areas in a stunted form, deformed by the winds, in marked contrast with the upright tree which becomes in more sheltered areas.
The High Dunes
Most nutrients have leached from the high dunes by rain waters and the soils are thus infertile in the agricultural sense. These dunes, however, generally support tall open forests, dominated by eucalypts, with a well-developed understory of grasses and shrubs. The more common species of eucalypts include blue gum (Eucalyptus tereticornis);scribbly gum (E. signata); pink and red bloodwoods (E. intermedia and E. gummifera) and blackbutt (E. pilularis). Other trees of the open forests include the smooth-barked apple (Angophora costata); the she-oaks (Casuarina littoralis and C. torulosa); the cypress-pines (Callitris columellaris and C. rhomboidea). Smaller trees and shrubs include several wattles or acacias such as the black wattle (Acacia cunninghamii); sweet wattle (A. suaveolens), prickly moses (A. ulicofolia) and the wallum and coastal banksias(Banksia aemula and B. integrifolia). These banksias and some of the eucalypts attract many nectar-eating birds and insects when flowering.
Shrubs of the understory include May-bushes or Tea-trees (Leptospernum) and baeckea species with masses of small white flowers; geebungs (Persoonia) species with yellow or cream flowers; wedding bush (Ricinocarpus pinifolius) which can provide a spectacular spring show with masses of white flowers; grass-trees or blackboys (Zanthorrhoea Johnsonii) with striking spear-like flowering spikes which are attractive to nectar-eating birds and insects, and the blueberry ashes (Elaeocarpus obovatus and E. reticulatus ).
Many smaller flowering shrubs and creepers also occur, including the pink flowering boronia (Boronia rosmarinifolia); eggs & bacon (Dillwynia floribunda); the yellow pea(Phyllota phylicoides) and false sarsparilla (Hardenbergia violacea). The well-known bracken fern (Pteridium esculentum) is widespread, as is the matrush (Lomandra longifolia).
Mangroves conspicuously occupy the inter-tidal zone along the western side of the island, ranging from isolated trees to extensive forests in the south and in Swan Bay. The common and dominant species is the grey mangrove (Avicennia marina), but stilted mangrove (Rhizophora stylosa), large-leafed mangrove (Bruguiera gymnorrhiza), spurred mangrove (Ceriops tagal), river mangrove (Aegiceras corniculatum), and the milky- sapped blind-your-eye (Exoecaria agallocha) are all well distributed. Areas of muddy sand adjacent to the mangroves support several species of seagrass, of which Zostera capricornia) the most abundant.
Information from otes On North Stradbroke Island and North Stradbroke Island Visitors’ Guide by John Liddy