Native to Eastern Brazil Alcantarea are in subfamily Tillandsioideae of family Bromeliaceae.
World Flora Online and Plants of the World Online recognise around 43 species while others estimate 20 or 50.
Those sold in Australia include Alcantarea australiana, A. extensa, A. geniculata, A. imperialis, A. odorata
and A. vinicolor and their cultivars.
The Giant or Imperial bromeliad is native to Brazil.
They are among the largest of all bromeliads with vegetative parts 1 to 2 m high and wide and inflorescences
up to 2 or 3 m tall.
In nature they typically grow on rocks but under cultivation they are mostly terrestrial.
They have a short woody stem and being such large plants they have a strong root system to support them.
On the stem the spirally arranged leaves form a tight funnel-shaped rosette that holds water and organic debris.
The broad leaf sheaths are covered in dark scales.
At the sheath blade junction there is a flap of tissue called a ligule.
The thick tough linear to oblong blade can be over 1 m long and is 12 to 15 cm wide.
The purplish tip is a long point that curls back up to 180 degrees.
The blade is slightly ribbed and there are no spines.
The leaf colouration is very variable.
The upper surface can be green often with a waxy coating giving a bluish or grey appearance.
The base usually has pale purple blotches or is all purple.
The lower surface is dark red to purple.
The upper surface is smooth and the lower has some small scales.
Flowers are on a much-branched pyramidal panicle up to 1.5 m long and 45 cm wide at the base.
This is on a thick red leafless and slightly curved stalk or scape.
The scape is covered by tough overlapping reddish scape bracts whose tips curve under.
The slightly arching reddish side branches are 20 to 40 cm long.
At the base of each is a reddish primary bract around 7 cm long with a pointed tip.
The flowers, basically in 2 ranks open from the base of the branch up.
A plant can have hundreds of spreading narrow tubular flowers each on a stalk up to 1 cm long.
The rigid ovate upward curved floral bract below each flower has a pointed tip and a keel.
Around 2 cm long they can be green, purple or yellow.
There are 3 reddish elliptic to lanceolate sepals 4 to 5 cm long with a pointed tip.
The 3 linear petals are around 10 cm long with 2 large scales on the inner base.
When the flower opens the widely spreading petals are firm and yellow.
As the flower matures the petals become droopy and cream or white.
There are 6 stamens in 2 whorls with the white filaments almost as long as the petals.
The ovary has 3 locules and a single straight style that is longer than the stamens.
The nectaries at the base of the ovary produce a large amount of nectar.
The fruit are berries around 5 cm long with small seeds having a feathery bunch of hairs.
Before the plant eventually dies it produces offsets to replace itself.
Going on the colour of the leaves and bracts numerous green, red and purple varieties and cultivars are sold.