Subfamily Tillandsioideae of Family Bromeliaceae has around 1,500 species.
The better known genera are Tillandsia, Guzmania and Vriesea.
They are typically epiphytes having leaves with no teeth or spines and septicidal capsules with feathery seeds.
Tillandsia is the largest genus with over 650 species native to the warmer areas of North and South America.
Almost all Tillandsia are epiphytes using trees for support while some live on rocks.
What roots they have are only used to attach them to some support.
Many are small plants from 2.5 to 25 cm high but the largest can be up to 1 m or more.
The stem may have no branches, a few or there may be many basal branches forming a dense clump.
Narrow linear to lanceolate or triangular leaves are alternately arranged most commonly in a spiral.
They can be in a tight bundle, a basal rosette or along the stem in 2 or more ranks.
In some basal rosettes the long overlapping leaf sheaths are so tight the rosette holds water and debris.
Leaves are 2.5 to 70 cm long although most are under 10 cm.
The thinnest are only 1 mm wide while the largest are up to 7 cm across.
The overlapping sheaths are mostly long with some up to 25 cm.
The largest rosettes, with up to 40 leaves can be 1 m across although most are much smaller.
The leaves just below an inflorescence may colour when the plant flowers.
With no roots water and nutrients are absorbed from their surroundings through specialised scale-like hairs or trichomes.
These are dense on plants growing in dry conditions making the leaves grey, white or silvery.
Plants in wet or humid conditions have green leaves with few or no trichomes.
The terminal inflorescences are usually on an obvious erect or slightly curved leafless stalk or scape.
The commonly dense and overlapping bracts on the scape are up to 35 cm long.
Linear, obovate to elliptic and green or coloured they may have a few scales.
The inflorescences are varied.
Pyramidal inflorescences have a central axis or rachis with flowers on side branches.
Spikes have single flowers along the central axis in 2 or more ranks.
Occasionally there is only 1 (2) flower on a stalk.
Inflorescences are a few cms up to 35 cm long.
Branched inflorescences have 1 to 3 bracts at the base of each branch.
They are smaller than the scape bracts but brightly coloured in red, yellow, pink or purple.
Flowers, on a short or no stalk have small floral bracts below them and along the stems.
Up to 5.5 cm long and 3 cm wide these bracts are usually longer than the sepals.
They are ovate to elliptic with a marked keel or ridge and they may have some scales.
The bisexual mostly tubular flowers have 3 alternating sepals and petals.
The sepals, up to 3 cm long are usually free but may be joined at the base.
Ovate, lanceolate or elliptic they have a keel on the posterior surface.
They are smooth outside but have a few to many scales on the inner surface.
The petals are free, up to 6 cm long with a wide linear base or claw and a broader elliptic blade.
As well as white petals can be blue, yellow, orange, violet, pink, red or green.
Occasionally the petals have 2 colours such as purple and white.
There are 6 stamens in 2 whorls of the same or different lengths.
The superior ovary, with many ovules has a single style with a straight or spirally twisted stigma.
The anthers and stigma can lie within or outside the corolla tube.
The fruit are cylindrical septicidal capsules 1 to 4 cm long.
The seeds, only a few mms long are on a long stalk.
The plume of white hairs, attached to the base of the stalk surround the stalk and seed.
New plants can grow from fragments that break off.
After flowering the plant forms offsets or pups then dies.