Xanthostemon 
Pedicels 4-6 mm long. Flowers 5-merous. 
Hypanthium c. 2.5 mm long, 4.5 mm wide. Calyx 
lobes narrowly triangular, 2-3 mm long. Petals 
cream, the blades orbicular to elliptic, 2.5-4 mm 
long. Stamens cream, in a single whorl, free, c. 7 mm 
long. Fruit depressed globular, 5-6 mm diam., 
puberulous. Flowering: Feb - June; fruiting: most 
months. Fig. 57 
In disjunct populations from Arnhem Land to 
the Kimberley. In the DR known only from Melville 
Is. where it is found on weathered sandstone and 
laterite. In the Alligator Rivers region it forms stands 
in sandstone gorges. 
X. umbrosus (A.Cunn. ex Lindl.) Peter Wilson & 
J.T.Waterh. 
Tristania umbrosa A.Cunn. ex Lindl. 
Metrosideros tetrapetala F.Muell. 
Tree, often multistemmed or shrubby, to 14 m 
MYRTACEAE 183 
high; bark smooth, mottled grey and cream. 
Branchlets quadrangular, pubescent. Leaves 
decussate; petioles 2-10 mm long, finely pubescent; 
blades discolorous, elliptic, 45-85 mm Jong, 25-40 
mm wide, pubescent to glabrescent below, glabrous 
to glabrescent above, base attenuate, apex obtuse. 
Inflorescence corymbose, puberulous throughout. 
Flowers 4-merous; pedicels 6-10 mm long. 
Hypanthium c. 1.5 mm long, 3-4 mm wide. Sepals 
triangular, 2.5-3 mm long. Petals cream, blades 
+ orbicular, 3-3.5 mm long, pubescent below, gla- 
brous above. Stamens cream, in 2 whorls, free, 
4-5 mm long. Fruit globose or + depressed globose, 
7-9 mm diam., glabrous. Flowering: Mar; fruiting: 
Mar - July. Fig. 57 
Distributed from the Kimberley to Qld. In the NT 
in the Alligator Rivers region and Groote Eylandt; 
not recorded in the DR. In monsoon thickets, usually 
on sandstone. 
RHIZOPHORACEAE 
G.M. Wightman 
Trees or shrubs, evergreen, viviparous (except Carallia), stilt roots and variously shaped 
pneumatophores often present. Stipules interpetiolar, deciduous. Leaves decussate, simple, petiolate, 
coriaceous, entire or serrulate, glabrous. Inflorescence cymose or flowers solitary, usually axillary. 
Flowers usually subtended by bracteoles, bisexual, actinomorphic, 4-5(16)-merous, perianth and 
stamens hypogynous or epigynous arising from hypanthium. Calyx persistent, valvate. Corolla 
often caducous. Stamens usually twice as many as corolla lobes, often in pairs opposite the petals; 
anthers 4-multi-locular. Ovary 2-8-locular; ovules 2 per locule, pendulous; style simple; stigma 
simple or variously lobed. Fruit fleshy or leathery, indehiscent. Seed 1. Hypocotyl elongate. 
A family of about 16 genera and 120 species of tropical distribution. Four genera in the NT, all in the DR; 
all are mangroves except Carallia. [Ding Hou, 1958; McCusker, 1984; Wightman, 1989] 
1. Trees of non-maritime habitats; not viviparous; petals ClaWed .......sesssesseseeseseesteeeeneenens Carallia 
1. Trees or shrubs of mangrove habitats; viviparous; petals not clawed .......s:ssseresssseeseesees 2 
2. Trees supported by stilt roots; calyx 4-lobed; petals entire ........c.ccseseseeeteesteneeeeneeeeeeeeees Rhizophora 
2. Trees and shrubs without stilt roots; calyx 5-16-lobed; petals lobed 3 
4}, Trees; knee roots often present; calyx 8-16-lobed; petals bifid or emarginate ..............4... ; Bruguiera 
A} Shrubs or small trees; knee roots never present; calyx 5-6-lobed; 
petals ifringed[ore3-lobed Memnnmiriritimiercrininitartttetesrictstiststel st Ceriops 
BRUGUIERA Lam. 
Large shrubs or trees; base often buttressed, pneumatophores knee-like. Leaves black-dotted beneath. 
Inflorescence 1-10-flowered; bracteoles absent. Sepals and petals 8-16; petals each embracing 2 stamens, 
