What are bromeliads

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Ananasstaude.JPG
Nobody should presume he does not know any „Bromeliads“. For at least one species - in fact being not an ornamental but an economic plant - is on the tip of everybody’s tongue: the pineapple. She was the first representative of her family to find her way to Europe, rather soon after the discovery of America. The Bromeliads (lat.: Bromeliaceae) obtained their name by the French botanist Charles Plumier who published them 1703 [1] for the first time, naming them after his friend, the Swedish physician and botanist Olaf Bromel (1639-1705). In german language generally the name “pineapple plants” is in use.


Distribution

Distribution map
Bromeliads are growing exclusively in the New World, which means North and South America. Solely the species Pitcairnia Feliciana also exists in the western Africa. The distribution area of Bromeliads ranges from the South of the USA over Central America far down to Argentina and Chile. They thrive in nearly every living environment, including all deserts of the Western Hemisphere, even inclusive of the desert most arid in the world, the Atacama. Wether moist and hot lowland rainforests, dry cactus and thorn forests, or moist and could rain- and cloud forest of the mountains, even on the table mounts of Venezuela (Tepuis) and in the Páramos of the Andes, more than 4000m high, are to be found Bromeliads.


Ecology

About half of the known Bromeliad species live epiphytic, meaning they grow on other plants, but without feeding on them. They are no parasites, what they are often erroneously called and - alas - are treated likewise by locals. However Bromeliads can also be found living on rocks (litophytic) or on the ground (terrestrial). As their habitats dry out severely sometimes, some of them started building a funnel or a cistern with the use of the leaf bases, to catch and keep water. The biggest species can this way store up several liters of water, which assists them to compensate rather long dry periods. At the same time these minuscule lakes represent a self-contained biotope and provide living space for several other creatures, often to the benefit of both. The funnels serve insect species as breeding place for their nymphs, tropical tree frogs live and spawn in them, and even several water plants grow there. Even crabs have been found in Bromeliad cisterns. In nutrient-poor regions a few Bromeliads actually have developed the ability to live as carnivores. The pollination of the flowers is carried out by animals, especially birds as well as butterflies or other insects. Only species of Navia are pollinated by wind. Some Bromeliads specialized on particular groups of pollinators. For example Werauhias are pollinated by bats, they blossom in the night, when these animals are on the hunt.


Habit and Leaves

As varied as their dissimilar habitats are size, shape and texture of these plants. Not only within the family, even in one genus size and shape can vary that much you never would believe they are relatives. The size ranges from a few millimeters to several meters.

Bromeliads are indeciduous, hardy herbaceous perennials. Rarely species occur which drop their leaves 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 foliage with parallel venation is arranged alternate and spiraled, 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 leaf 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 trichomes) on their leaves. Depending on habitat and way of life the scales enclose the leaf 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 it reflects the sunlight and by that they reduces the loss of water caused by evaporation. At the same time it multiplies the surface of the leaf to a great extent and thereby enlarges 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 into 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

Puya raimondii
Like all other monocotyledonous plants Bromeliads always have trifoliate flowers. That indicates that the number of all organs of the plant is divisible by three. That is: Three sepals, three petals, six stamens and the ovary, consisting of three carpels. Often the signaling to attract potential pollinators is increased by very decorative bracts. Bromeliads predominantly are bisexual, that means they have male organs as well as female organs in one flower. Only a small number of species produce unisexual flowers. They are called dioecious, meaning the whole plant is either male or female (f. e. the genera Androlepis, Hechtia and some species of Catopsis and Aechmea). In Bromeliads scent occurs regrettably seldom. The inflorescences are plain or compound racemes or panicles shaped very differently. Whereas the genus Neoregelia builds his flowers sunken deeply in the cistern, sometimes even hard to spot, the inflorescence of Puya raimondii with her thousands of individual flowers may be higher than 8 (!) meters. This species has, by the way, made it’s way into the “Guinness book of records” as the plant with the tallest inflorescence in the world.


Fruits and Seeds

Bromeliads form dry capsules or berries. The fruits often represent an essential criterion for classification. An exceptional position is thereby reserved to the pineapple. Her "fruit" consists actually of an edible composite of fruits (Synkarpium), wherein the individual fruit can hardly be distinguished. The berries stay closed even at the state of maturity. They are eaten by animals which excrete the seeds undigested and thus spread them widely. In contrast the capsules form winged seeds or parachute-like appendixes which are distributed by the wind.


Taxonomy

The family of the Bromeliaceae subsumes as now about 60 genera and approximately 3000 species. Until some years ago they were separated in three subfamilies.

Tillandsioideae: With dry capsules and seeds with parachute-like appendixes, leaf edges generally smooth and not spiny.
Most known taxa: Tillandsia, Guzmania, Vriesea and Catopsis
Bromelioideae: Sole subfamily with berries and seeds without appendixes, leaf edges usually spiny.
Most known taxa: Aechmea, Ananas and Neoregelia
Pitcairnioideae: Carrying dry capsules and usually winged seeds, leaf edges mostly spiny.
Most known taxa: Puya, Pitcairnia

Based on the latest researches (2007-2011) further subfamilies will be added, splitting the subfamily Pitcairnioideae and increasing the number of subfamilies to eight.[2][3]


Utilization

Only a few species of the Bromeliaceae are in service as a useful plant. Without question the biggest commercial relevance the pineapple draws on itself. Also the fruits of the Bromelia karatas, common in the Caribbean, are edible and very tasty. The stems of Bromelia karatas and Bromelia laciniosa (called "Macambira" in Brasilia) after cooking and drying at the sun provide a starch flour, and the hearts of some Puya species of the Andes are used as salad and are the favourite dish of the Andean bear (Tremarctos ornatus).

In addition to the fruits Ananas species provide fibers which are converted to ropes and lashings as well as first-class textiles and paper[4]. In the Philipines the traditional.men’s shirt "Barong Tagalog" [5] are manufactured out of them. Some other Bromeliads are used similarly for the production of fibers, as for example Neoglaziovia variegata same as Deinacanthon urbanianum.

From plant parts of Ananas species is segregated the protein-dissociative enzyme Bromelain, which is used for turning meat tender (many other species may be used for that, because Bromelaines are common in the family). The Louisiana moss (Tillandsia usneoides) serves as packing and stuffing material.

Out of the approximately 3000 species which are today known at least 500 are culture worthy houseplants. Most frequently cultivated for sale are Aechmea fasciata, Guzmania- and Vriesea hybrids and the well-known Vriesea splendens.


Sources

References

  1. Jason R. Grant An Annoted Catalogue of the Generic Names of the Bromeliaceae, In: The Marie Selby Botanical Gardens, 1998.
  2. T. J. Givnish, J. C. Pires, S. W. Graham, M. A. McPherson, L. M. Prince & T. B. Patterson: Phylogeny, biogeography, and ecological evolution in Bromeliaceae: Insights from ndhF sequences. in J. T. Columbus, E. A. Friar, J. M. Porter, L. M. Prince, & M. G. Simpson: Monocots: Comparative Biology and Evolution. Poales, Rancho Santa Ana Botanical Garden, Claremont, 2007, 23, page 3-26.
  3. Thomas J. Givnish, M. H. J. Barfuss, B. Van Ee, R. Riina, Katharina Schulte, Ralf Horres, P. A. Gonsiska, R. S. Jabaily, D. M. Crayn, J. A. C. Smith, K. Winter, Gregory K. Brown, T. M. Evans, Bruce K. Holst, Harry E. Luther, Walter Till, Georg Zizka, P. E. Berry & Kenneth J. Sytsma: Adaptive radiation and diversification in Bromeliaceae: insights from a 7-locus plastid phylogeny, In: American Journal of Botany, Volume 98, Issue 5, 2011, S. 872-895: PDF.
  4. The Blue Pineapple Story - paper made from pineapple fibres
  5. Barong Tagalog in Wikipedia