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Rhizophora apiculata

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Rhizophora apiculata mature hypocotyl, Cairns, QLD. Photo: F.Zich © CSIRO

Common Names

Corky Stilt Mangrove ([1]), Tall Stilt-root Mangrove ([2]), Tall-stilted Mangrove ([3]).

Family

Rhizophoraceae

Name ref

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Rhizophora apiculata forest, Cairns, QLD. Photo: F.Zich © CSIRO

Rhizophora apiculata Blume

Origin of Name

Rhizo-phora means 'root bearing' in Greek, referring to the stilt roots characteristic of the genus.

apiculata means 'to end abruptly' in Latin, referring to the leaf apex ([1], [2]).

Synopsis

Rhizophora apiculata is a large tree with conspicuous stilt roots, dark green leaves and paired flowers with corky bracteoles. It is found in mangroves across the top end of the Northern Territory, through to Port Clinton, Queensland.

Botanical Description

Rhizophora apiculata is a columnar or multi-stemmed tree growing to 25 m high. It has rough brown to dark grey or black bark, often with the appearance of crocodile skin with angular patches separated by fissures. It has stilt roots extending up to 3 m up the stem from the ground. Aerial roots extend downwards from branches. The stem base is diminished below the stilt roots.

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Glossy, dark green elliptic leaves with a pointed tip. Photo: F.Zich © CSIRO

The leaves are simple, opposite, narrowly-elliptic to elliptic in shape, glossy dark green above with a distinct light green zone along the midrib and dull below, 7 - 19 cm long and 3 - 9 cm wide with a pointed apex and mucronate spike to 6 mm long. The petiole is 1 - 4 cm long. Under surface spots are absent.

The inflorescence is axillary with 2 (occasionally up to 4) yellowish-green or cream flowers which are held below the leaf clusters. The bracteoles are completely united into a bulbous, brown, corky cup. The flowers have 4 calyx lobes and 4 non-hairy greenish-white petals.

The fruit is a brown, corky, inverted pear-shape which grows a cylindrical and slightly club-shaped hypocotyl. The hypocotyl is 18 - 40 cm long and 1 - 2 cm wide ([3], [2], [1], [4], [5] ).

Distribution

Distributed from India and Sri Lanka, throughout Asia and into the western Pacific and northern Australia. In Australia, Rhizophora apiculata is found from Melville Island in the Northern Territory to Port Clinton, Queensland ([1]).

Localities (not complete):

Habitat

Prefers less saline conditions so found in middle to upper tidal reaches of estuaries in wetter parts of the north coast ([1], [3]). Grows in mud and sand ([2]).

Biology

In Australia, peak flowering occurs from April to May, with propagule maturation from January to February ([1]). In the Northern Territory flowering and fruiting occurs sporadically, year round ([12]).

In middle estuary locations it is often found with Rhizophora stylosa, Bruguiera gymnorhiza and Xylocapus spp. in northern areas. In upper tidal areas it is often found with Rhizophora mucronata. The most developed stands are found in the middle estuarine areas and are often monotypic ([1]). In the Northern Territory additional associates include Lumnitzera littorea and Rhizophora X lamarckii ([2]).

This species can form natural grafts where the roots of two trees of the same species touch ([3]).

All Rhizophora flowers are thought to be wind pollinated ([13]).

Biological Interactions  
Group Taxon
  28 taxa
Vascular Plants Acrostichum speciosum
Vascular Plants Aegialitis annulata
Vascular Plants Aegiceras corniculatum
Vascular Plants Avicennia marina
Vascular Plants Bruguiera cylindrica
Vascular Plants Bruguiera exaristata
Vascular Plants Bruguiera gymnorhiza
Vascular Plants Bruguiera parviflora
Vascular Plants Bruguiera sexangula
Vascular Plants Camptostemon schultzii
Vascular Plants Ceriops pseudodecandra?
Vascular Plants Ceriops tagal
Vascular Plants Cynometra iripa
Vascular Plants Diospyros geminata
Vascular Plants Excoecaria agallocha
Vascular Plants Heritiera littoralis
Vascular Plants Hibiscus_tiliaceus
Vascular Plants Lumnitzera littorea
Vascular Plants Lumnitzera racemosa
Vascular Plants Nypa fruticans
Vascular Plants Osbornia octodonta
Vascular Plants Rhizophora X lamarckii
Vascular Plants Rhizophora mucronata
Vascular Plants Rhizophora stylosa
Vascular Plants Scyphiphora hydrophylacea
Vascular Plants Sonneratia alba
Vascular Plants Xylocarpus granatum
Vascular Plants Xylocarpus moluccensis

Ethnobotany

Valued as a forestry species in Malaysia for domestic construction timber and production of charcoal fuel ([1]).

In the Northern Territory mangrove worms can be found in the wood and mud crabs amongst the roots ([12]).

For further ethnobotanical information see [2].

Similar Species

Rhizophora can be distinguished from other genera in the Rhizophoraceae family by the number of calyx lobes (4). Ceriops spp. have 5 calyx lobes while Bruguiera spp. have 8-15. Rhizophora also have large stilt roots compared to the smaller buttresses, knee and prop roots found in Ceriops and Bruguiera and leaves with mucronate tips ([1]).

Rhizophora apiculata can be distinguished from other Rhizophora species by it's large apiculate, glossy dark-green leaves; paired flowers, which hang below the leafy crowns; corky, swollen bracteoles of flowers and fruits; lack of brown spots on the leaf under-surface; usually 11 - 12 stamens; styles usually less than 1 mm; and, bark that often looks like crocodile skin ([1]).

For illustration and further description of the above distinguishing characters see Mangrove Watch Australia: http://www.mangrovewatch.org.au/index.php?option=com_content&view=category&layout=blog&id=39&Itemid=300175

Mangrove Watch: http://www.mangrovewatch.org.au/index.php?option=com_content&view=category&layout=blog&id=39&Itemid=300175

Flora of Australia Online: http://www.anbg.gov.au/abrs/online-resources/flora/stddisplay.xsql?pnid=6949

Zipcode Zoo: http://zipcodezoo.com/Plants/R/Rhizophora_apiculata/

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Corky brown, inverted-pear shaped fruit with emergent hypocotyl. Photo: F.Zich © CSIRO

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Rhizophora apiculata propagule, Singapore. Photo: John Yong

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Rhizophora apiculata propagule, Singapore. Photo: John Yong

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Rhizophora apiculata (Bottom left). For comparison, Rhizophora mucronata (longest propagule) is placed in the middle, with Rhizophora stylosa on the right. Photo: John Yong

References

  1. Duke, N.C. (2006). Australia's Mangroves. The authoritative guide to Australia's mangrove plants. University of Queensland, Brisbane. (more)
  2. Wightman, G. (2006). Mangroves of the Northern Territory, Australia: identification and traditional use. Northern Territory. Dept. of Natural Resources, Environment and the Arts, Palmerston. (more)
  3. Lovelock, C. (1993). Field Guide to the Mangroves of Queensland. Australian Institute of Marine Science, Townsville, Qld. Available online: http://www.aims.gov.au/c/document_library/get_file?uuid=c9dcfc2e-6018-4302-8818-5ab3fe01f91f&groupId=30301 (more)
  4. !McCusker, A. (1984). Rhizophoraceae. Flora of Australia. 22: 1-10. (Australian Government Publishing Service: Canberra.) (more)
  5. Ding Hou (1958). Rhizophoraceae. Flora Malesiana. Ser. 1, Vol. 5, (P. Noordhoff Ltd: Groningen.), pp. 429-493. (more)
  6. Bunt, J.S. (1982b). Mangrove Transect Data from Northern Queensland. Coastal Studies Series, Australian Institute of Marine Science AIMS-CS-82-1. Australian Institute of Marine Science. 41 p. Available online: http://data.aims.gov.au/extpubs/attachmentDownload?docID=2326 (more)
  7. Smith III, T.J. (1987). Seed predation in relation to tree dominance and distribution in mangrove forests. Ecology 68(2): 266-73. Available online: http://www.jstor.org/stable/pdfplus/1939257.pdf (more)
  8. Robertson, A.I., Giddins, R. and Smith, T.J. (1990). Seed predation by insects in tropical mangrove forests: extent and effects on seed viability and the growth of seedlings. Oecologia 83: 213-219. Available online: http://www.springerlink.com/content/h6567208r2v14176/fulltext.pdf (more)
  9. Bunt, J.S. (1997). The Mangrove Floral and Vegetational Diversity of Hinchinbrook Island and the Adjacent Coast. Australian Institute of Marine Science, Townsville. Available online: http://data.aims.gov.au/extpubs/attachmentDownload?docID=3018 (more)
  10. Boto, K. G. and Wellington, J. T. (1983). Phosphorus and nitrogen nutritional status of a northern Australian mangrove forest. Mar. Ecol. Prog. Ser. 11: 63-69. Available online: http://www.int-res.com/articles/meps/11/m011p063.pdf (more)
  11. Boto, K.G., Bunt, J.S. and Wellington, J.T. (1984). Variations in mangrove forest productivity in northern Australia and Papua New Guinea. Estuarine Coastal and Shelf Science 19(3): 321-329. Available online: http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WDV-4DV0KPV-CY&_user=2322062&_coverDate=09,2F30,2F1984&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1655468263&_rerunOrigin=google&_acct=C000056895&_version=1&_urlVersion=0&_userid=2322062&md5=09397a6e327acf15899ed3f7ddc83a82&searchtype=a (more)
  12. Wightman, G. (2006b). Mangrove Plant Identikit from north Australia's Top End. Greening Australia NT, Darwin. (more)
  13. Tomlinson, P.B. (1986). The Botany of Mangroves. Cambridge Tropical Biology Series. Cambridge University Press, Cambridge. (more)

Biological Interactions
Relation Taxon GroupSorted ascending
HasEpiphyte Pyxine_farinosa Lichens
HasEpiphyte Pyxine_keralensis Lichens
HasEpiphyte Ramalina_confirmata Lichens
OccursWith Ceriops_pseudo? [[Mangroves.][]]
OccursWith Acrostichum_speciosum Vascular_Plants
OccursWith Aegialitis_annulata Vascular_Plants
OccursWith Aegiceras_corniculatum Vascular_Plants
OccursWith Avicennia_marina Vascular_Plants
OccursWith Bruguiera_cylindrica Vascular_Plants
OccursWith Bruguiera_exaristata Vascular_Plants
OccursWith Bruguiera_gymnorhiza Vascular_Plants
OccursWith Bruguiera_parviflora Vascular_Plants
OccursWith Bruguiera_sexangula Vascular_Plants
OccursWith Camptostemon_schultzii Vascular_Plants
OccursWith Ceriops_pseudodecandra Vascular_Plants
OccursWith Ceriops_tagal Vascular_Plants
OccursWith Cynometra_iripa Vascular_Plants
OccursWith Diospyros_geminata Vascular_Plants
OccursWith Excoecaria_agallocha Vascular_Plants
OccursWith Heritiera_littoralis Vascular_Plants
OccursWith Hibiscus_tiliaceus Vascular_Plants
OccursWith Lumnitzera_littorea Vascular_Plants
OccursWith Lumnitzera_racemosa Vascular_Plants
OccursWith Nypa_fruticans Vascular_Plants
OccursWith Osbornia_octodonta Vascular_Plants
OccursWith Rhizophora_X_lamarckii Vascular_Plants
OccursWith Rhizophora_mucronata Vascular_Plants
OccursWith Rhizophora_stylosa Vascular_Plants
OccursWith Scyphiphora_hydrophylacea Vascular_Plants
OccursWith Sonneratia_alba Vascular_Plants
OccursWith Xylocarpus_granatum Vascular_Plants
OccursWith Xylocarpus_moluccensis Vascular_Plants
OccursWith Xylocarpus Vascular_Plants