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 18 leafy in the dry season DHJanzen100100.jpg high resolution
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| A single ant-acacia in full leaf in the full dry season, when all the other foliage in its vicinity (easily 20 other species of plants) is essentially leafless (deciduous). By retaining its leaves throughout the dry season (which presumably has its cost in deeper roots, more waxy leaf cuticles, greater resistance to herbivory, and ??), the ant-acacia maintains a full and healthy acacia-ant colony. The large leaves (produced during the previous rainy season) long since have had their Beltian bodies eaten off, but continue to produce foliar nectar daily. The continuous crop of Beltian bodies is produced by producing shoots with dwarfed leaves (and often minute non-swollen thorns) but full-sized Beltian bodies. Living space is not in sufficiently short supply that new swollen thorns are produced in the full dry season. The leaves may also shade the swollen thorns to some degree, reducing overheating and desiccation of the ants. This phenomenon is most visible on the dry (desert edge) margins of the ant-acacia distributions in Mesoamerica, and probably of trivial importance on the wet (rainforest edge) of the ant-acacia distributions. Being green in the dry season, however, emphasizes the importance of the acacia-ant colony as an anti-herbivore device which is probably more effective than almost any combination of chemicals and spines for a leafy plant in a seasonally dry habitat (cacti, orchids and bromeliads excepted). | ||
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