130 HALORAGACEAE 
Myriophyllum 
1. Emergent leaves toothed in upper half, intermediate leaves absent; 
flowers bisexual; mericarps flattened with longitudinal wings extending 
down'the:dorsal[Surfac€ sisrsnscecssetsteesossteccecesecttocsssts 
M. muricatum 
1. Emergent leaves entire, divided, intermediate leaves often present; 
monoecious with male flowers in upper axils and female below; 
mericarps cylindrical, tuberculate in lower half ..... 
M. muricatum Orchard 
M. tuberculatum Roxb., misapplied name 
Stems c. 4 mm diam. with roots only at base. Sub- 
merged Jeaves in sometimes irregular whorls of 4-6, 
finely pectinate, 25-50(70) mm long, 20-40 mm wide 
with numerous filiform pinnae 6-25 mm long. Emer- 
gent leaves irregularly arranged to almost in whorls, 
linear to narrowly oblanceolate, 7-20 mm long, 1-1.5 
mm wide, toothed in upper half, acute. Flowers 
bisexual, solitary in the axils of emergent leaves. 
Bracteoles brown, c. 1 mm long, linear. Sepals 
minute, orbicular. Petals thin, c. 2 mm long, persist- 
ing to early stages of fruit development. Anthers on 
a short filament about as long as the petals. Ovary 4- 
angled (ribbed), minute. Fruit globular, c. 2.5 mm 
long, square in cross-section with longitudinal wings 
extending down the dorsal surface of each mericarp, 
mericarps flattened semi-circular, each with a + 
inflated membranous exocarp which weathers to 
reveal the numerous short woody spines of the 
endocarp. Flowering and fruiting: Feb - Oct. Fig. 39 
Found in the NT north of 13°S and also in subcoastal 
central and northern Qld. In the DR known from Fogg 
Dam and the Reynolds River. Grows in permanent 
billabongs and seasonally inundated swamps in 
water to | m deep. Closely related to the Indian 
species M. tuberculatum Roxb. to which collections 
from the NT had previously been referred. 
Myriophyllum 
M. trachycarpum 
M. trachycarpum F.Muell. 
Stems often red in emergent parts, yellowish-green 
in submerged parts. Leaves irregularly arranged. 
Submerged leaves often appearing to be in whorls of 
4-5 or scattered along the stem, pectinate, 10-25 mm 
long with numerous filiform pinnae to 17 mm long 
arranged irregularly along a slender rachis. Emergent 
leaves alternate, reddish, linear to oblanceolate, 
2-12 mm long, 0.4-1.5 mm wide, entire, apex blunt 
with reddish gland. Transitional leaves present, 
serrate to pinnate, sometimes longer than emergent 
leaves. Flowers monoecious, solitary in the leaf ax- 
ils; upper flowers male, lower female. Bracteoles lin- 
ear, 0.6-0.7 mm long. Male flowers lacking sepals. 
Petals linear, becoming reflexed after anthesis, 
c. 2.5 mm long, persistent. Female flowers lacking 
sepals, petals and stamens. Ovary pink, cylindrical, 
c. 0.6 mm long; stigmas white. Mericarps reddish, 
cylindrical, c. 1 mm long, | mm diam., bases rounded, 
covered in the lower 2/3 with tubercules, with 
oblique slightly flared apices. Flowering and 
fruiting: Apr - July. Fig. 39 
An Australian endemic, found in the Kimberley 
and the Top End of the NT. In the DR it is known 
from lagoons close to Darwin. Typically growing in 
shallow sandy creek channels associated with 
sandstone, but occasionally in lowland lagoons on 
sand or clay. 
1/20 cm 
M. trachycarpum 
