What are bromeliads: Difference between revisions
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Bromeliads are indeciduous, hardy herbaceous perennials. Rarely species occur which are deciduous in the dry season, like for example ''Pitcairnia heterophylla''. Her main shoot flowers only once and dies after the maturation of her seeds. This dieback takes place only gradually, because at the same time they produce replacing offshoots (called pups) which guarantee the continuance of the shoot system and can be used for multiplication. Only a few species die ultimately after bloom and maturity of the seeds. | Bromeliads are indeciduous, hardy herbaceous perennials. Rarely species occur which are deciduous in the dry season, like for example ''Pitcairnia heterophylla''. Her main shoot flowers only once and dies after the maturation of her seeds. This dieback takes place only gradually, because at the same time they produce replacing offshoots (called pups) which guarantee the continuance of the shoot system and can be used for multiplication. Only a few species die ultimately after bloom and maturity of the seeds. In the majority of cases the Bromeliads possess a compressed axis, of which results a leaf rosette as the typical shape. There exist some species though whose axis is not compressed and which develop small stems. | ||
The parallel nerved foliage is arranged alternate and convoluted, less commonly distichous, like in the subgenus ''Diaphoramthema'' of the genus ''Tillandsia''. The leaves usually do not own a leaf stalk (with the exception of some ''Pitcairnia'' species). The edges can be straight or spiny. Some Tillandsias curl up their leaf apexes like a corkscrew in order to cling onto the surrounding boughs aud branches. | |||
All representatives have in common the so called “absorbant hairs” or “scales” (foliar tri-chomes) on their leaves. Depending on habitat and way of life the scales enclose the leave partly or entirely and give it a striped design or a grey up to white shimmer. The pubescence thereby carries out more than one purpose. In sunny places they reflect the sunlight and by that they reduce the loss of water caused by evaporation. At the same time they multiply the surface of the leave to a great extent and thereby enlarge the accumulation of dew on the leaves in sites with low precipitation. The dew and it’s solute nutritive substances are absorbed by the trichomes like by blotting paper and are conveyed inside the leave. Some Bromeliads have perfected this technique to an extend that they almost dispense with roots and subsist exclusively by way of the scales, like the well known Louisiana moss (''Tillandsia usneoides''). | |||
== Roots == | |||
Like as in all monocotyledonous plants the main root dies shortly after the germination and so called adventitious roots are built. Plants living on the ground form a properly developed root system which contributes to feeding the plant with water and nutriment. On the contrary the epiphytic plants use their roots mainly to fix them on a surface. A few species (for example ''Tillandsia usneoides'') do not produce any roots after the primary root has perished. | |||
== Flowers and Inflorescences == | |||
[[file:Puya raimondii hábito.jpg|thumb]] | |||