Canna indica

Canna indica.

Known as the Wild canna lily or arrowroot it is an invasive weed in S.E. Queensland.
A perennial, clump-forming plant growing from rhizomes.
The green, unbranched, upright stems can be nearly 2 m high.
The leaves are alternate with narrowed bases sheathing the stem.
The ovate blades, up to 60 cm long by 30 cm wide have a pointed tip.

Inflorescences are spikes with up to 20 flowers at the top.
There are bracts up to 3 cm long and bracteoles to 2 cm.
Flowers are red or a yellow-orange.

The calyx has 3 narrow triangular, green sepals up to 1.7 cm long.
The 3 true petals are bract-like and up to 6.5 cm long by 0.7 cm wide.

The androecium has (3) 4 petal-like staminodes and a fertile stamen.
The 3 larger false petals are up to 6 cm long by 1.5 cm wide.
The other false petal, the labellum, is up to 5 cm long but only about 4 mm wide.
Its tip curves backwards.
The fertile stamen with a petal-like filament is up to 4 mm wide.
The half anther, about 10 mm long, is on the side.

The inferior ovary of 3 fused carpels has 3 locules and a spiky surface.
There are numerous ovules in each locule.
The apical style is slightly petaloid.

The fruit are ellipsoidal capsules covered in small projections which may disappear.
Capsules are up to 3 cm long by 2 cm wide, green then purplish then brown.
The withered perianth remains at the top.
The numerous smooth black seeds, up to 8 by 7 mm, have a very hard coating.

Varieties of C. indica.
Canna indica var. indica has red petals and long, narrow, red staminodes.

Canna indica var. warszewiczii is similar to C. indica var. indica but the green
    leaves have purple to red edges and the capsules are red to purple.
Two staminodes may be curved backwards like the fertile stamen.

Canna indica var. flava is yellow.

Canna indica var. maculata has green petals and the long, narrow staminodes are yellow with red spots.

Canna indica var. sanctae rosea has white edges on the green leaves and red petals.
The long narrow staminodes, the labellum, stamen and style are all pink.