Environmental influence on the inter- and intraspecific variation in the density and morphology of stomata and trichomes of epiphytic bromeliads of the Yucatan Peninsula

Abstract

We set out to test whether trichome and stomata variation in epiphytic bromeliads in the field would support the hypothesis that trichomes confer protection from excess light, increase water absorption and protect the stomata. We characterized the intra-and interspecific plasticity in the morphology and density of trichomes and stomata of 14 epiphytic bromeliad species found in six contrasting vegetation types (coastal sand dune scrub, scrub mangrove, pet en mangrove, and deciduous, semi-deciduous and semi-evergreen forest) on the Yucatan Peninsula along a precipitation gradient from 500 to 1500 mm (mean annual precipitation). We performed leaf impressions to determine trichome and stomatal density and to characterize morphology. Trichome morphology did not show variation between sites, but was distinctive for the species. Our data supported the existing hypothesis that trichome density and area were higher in the atmospheric species that inhabited the drier sites, compared with the wetter extreme, which may confer higher protection against photoinhibition and desiccation. Stomatal density increased with precipitation in tank species, and negatively correlated with vapour pressure deficit during the dry season. Fewer trichomes and greater numbers of stomata than expected by rainfall were found in mangroves that maintained low vapour pressure deficit during the dry season.

Morphophysiological Plasticity in Epiphytic Bromeliads Across a Precipitation Gradient in the Yucatan Peninsula, Mexico

“…There was less variation within the different physiological parameters measured in plants distributed in wetter sites than drier ones, even though the wetter semievergreen forest also experienced dramatic seasonal changes in VPD. The adverse conditions in the driest vegetation types, mainly at the coastal sand dune scrub (as the scrub mangrove maintained low VPD all year round, diminishing the effect of the dry period), was correlated to the development of different morphological modifications; for example, trichome density and size were higher in atmospheric bromeliad species distributed in drier sites than in wetter sites of the Yucatan Peninsula, probably playing a photoprotective role and aiding against desiccation by shielding the stomata (Cach-Pérez et al., 2016; Pierce, 2007).…”

High resilience to extreme climatic changes in the CAM epiphyte Tillandsia utriculata L. (Bromeliaceae)

“…In contrast, individuals of the scrub population showed traits related to water conservation, with narrower tanks that may diminish tank water evaporation, higher leaf succulence and lower stomata density. Yet, these anatomical differences among populations were small compared with those observed in other Tillandsia species from contrasting sites within the Yucatan Peninsula, which could show twice as many trichomes from one site to the other (Cach‐Pérez et al ).…”

“…Species from seasonal habitats have shown high plasticity in response to the naturally changing light, temperature and water availability within their environments or under experimental conditions (Martin et al , Haslam et al , Laube and Zotz , Bader et al , Reyes‐García et al , González‐Salvatierra et al , Cach‐Pérez et al ). Plastic traits may be anatomical, such as increased trichome density and size to decrease absorption of excess light or decreased stomatal density to reduce transpiration (Cach‐Pérez et al ) and physiological, such as decreased photosynthesis and growth rates in response to drought (Laube and Zotz , Bader et al , Reyes‐García et al ).…”

Dew Can Prolong Photosynthesis and Water Status During Drought in Some Epiphytic Bromeliads From a Seasonally Dry Tropical Forest

“…larger trichomes (Cach-Pe´rez et al, 2016). Together, leaf succulence, shape, angle, and trichome cover contribute to longer dew condensation time in T. elongata and a shorter time in T. yucatana.…”