Jump to content
Forum for Epiphytic Myrmecophytes

Brocchinia acuminata


Recommended Posts

Brocchinia Subfamily Brocchinioideae.

Brocchinia J. H. Schultes ex J. A. Schultes & J. H. Schultes in J. J. Roemer & J. A. Schultes published in Systema Vegetabilium 7(2) 1830.  Type Brocchinia paniculata Schultes J. H.  There are about twenty Brocchinia species now a sole genus in the subfamily Brocchinioideae.  Brocchinia diverged from very near the base of the Bromeliaceae about twenty million years ago.  (Givnesh et al. 2007.)

  All species are endemic to the Guyana Shield with a number of species restricted to the isolated ‘island’ like summits of tepui where they have adapted to environments so extreme that the word unique would be an understatement.  They are often pioneer plants - occupying the barest of bare habitats and several species are ecological dominants.

  One may perhaps form an impression from their basal placement and their immensely specialized, ecologically island-like habitats with severely limited dispersal potentials that the genus may have remained primitive.  Yet this is certainly not supported by the facts; indeed, there is enormous variety in this truly fascinating genus and although most Brocchinia species are beyond the scope of even a liberal overview such as this, those described will show just how advanced members of the genus have become.  I quote, “and most remarkably, Brocchinia has undergone an adaptive radiation in mechanisms of nutrient capture unparalleled at the generic level in angiosperms.  Brocchinia includes carnivores, ant-fed myrmecophytes, N² fixing symbionts, tank epiphytes and non-impounding terrestrial forms.” (Givnish et al.1984; Benzing et al. 1985; Givnish et al. 1985; cited by Givnish & Systma 1997.)  It is one of only two genera of flowering plants in which carnivory is present but not universal. (Givnish 1989 cited by Givnish & Systma 1997.)  Finally the genera’s diversity of nutritional strategies is accompanied by extensive variation in both the form and nutrient uptake capacity of its foliar scales or trichomes.” (Givnesh et al. 1984, Benzing et al. 1985, Owen et al. 1988 cited by Givnish & Systma 1997.)

"Absorptive trichomes are present in Brocchinia but in no other Pitcairnioideae (sic) and it is the only genus in this sub family to have evolved tanks."  (Givnish et al. 1997.)  It is not at all surprising that the placement of Brocchinia has now changed to Brocchinioideae.

Link to comment
Share on other sites

  • 2 months later...

Brocchinia acuminata Lyman Bradford Smith published in Brittonia 3, 1939.

  This terrestrial species is often larger than ‘bulbous’ Tillandsia species but it does have a somewhat analogous form with enclosed hollows in which ant colonies choose to reside.  Indeed, fifty percent of plants examined in habitat were ant occupied.  (Givnish et al.1997.)

However, here leaves are not as tightly closed above interior hollows as they are in Tillandsia, thereby allowing some water inside. This is perhaps because nutrient absorption inside the tanks of Brocchinia species occurs mostly through large, living, shield cells situated at leaf bases.  These cells can die if they become too dry - an important detail for cultivators. In Tillandsia, gas intake is performed through outer layers of dead cells that incorporate vapour gaps, which help to preclude the desiccation of the underlying living cells. (Givnish et al. 1997.)

  Hints that these are ant mutualists are provided by numerous adventitious roots that infiltrate their clustered leaf bases and trichomes are able to absorb the amino acids of decomposition.  Givnish et al., (1997) also postulates that it may be able to utilize internal supplies of concentrated carbon dioxide (CO²) from the respirations of ants and varied detrivore life forms as seen in Dischidia major.  Indeed, B. acuminata stomata are formed in sufficiently large clusters on internal leaf bases to be evident to the naked eye and although their function is not known, they do connect to aerenchyma channels (air-filled connective tissues) that are especially large in this species.  The plant’s photosynthesizing leaf tissues sit some 30 cm (12”) higher than where resident ant colonies are exhaling carbon dioxide. Perhaps the aerenchyma tubing transports this gas to where it is needed in photosynthesis. (Givnish et al. 1997.)

Habitats:  This, the most widespread of all Brocchinia species; occurs in tepui scrubs, edges of bogs, and cloud forests both on the top and lower surrounds of eastern and western tepui, hence at diverse altitudes between 600-2100 m (1969-6890 ft.). (Givnish et al. 1997.)

  Range:  Colombia and Venezuela. Type record, Venezuela, Edo Bolivar: Auyan tepui, at an altitude of 1850 m. (6070 ft.)

Link to comment
Share on other sites


This topic is now archived and is closed to further replies.

  • Create New...