Foliar epidermal anatomy and its taxonomic implications within the family Euphorbiaceae in the Niger Delta Region of Nigeria

Micro-morphological investigations of the foliar epidermal anatomy of seven species of the family Euphorbiaceae: Acalypha hispidia Burm. f., A. wilkesiana Mull. Arg, Euphorbia heterophylla L., E. hirta L., Jatropha curcas L., J. gossypifolia L. and Manihot esculenta Crantz was carried out to assess the systematic relevance of epidermal features, stomata and trichome diversity within the family using light microscope and camera. Members of this family contain many important medicinal herbs and there has been increasing misidentification of species in this family. Leaf micro-morphological characteristics are commonly used in the identification and authentication of plants. Results showed that the stomatal index varied from species to species. Epidermal cell shapes were found to be irregular to polygonal on both surfaces of the species. The epidermal cells possess straight to undulating anticlinal walls but in some few cases exhibited wavy to straight anticlinal walls. The presence of papillae was observed to be a unique character of E. heterophylla among the species studied. The stomatal types observed were Anisocytic, Anomocytic, Diacytic, tetracytic, paracytic, and actinocytic. The stomatal complex was mainly amphistomatic except for A. wilkesiana that was hypostomatic. The hypostomatic character of A. wilkesiana as reported in this paper is the first of such report as previous report found was amphistomatic. Non-glandular, multiseriate uniseriate and in some cases branched trichome types were observed only on both surfaces of A. wilkesiana and E. hirta but absent on all other studied species. This study revealed detailed descriptive micromorphological structures which could serve as a source of information and reference for the taxonomic description, identification and delineation of the species studied.

Bennettitalean Leaves From the Permian of Equatorial Pangea—The Early Radiation of an Iconic Mesozoic Gymnosperm Group

Bennettitaleans are an extinct group of gymnosperms that are among the most iconic plants of Earth’s vegetation during the Mesozoic Era. The sudden appearance and rise to dominance of the Bennettitales during the Triassic remains a mystery. Leaf fossils similar to typical bennettitalean foliage occur in late Paleozoic deposits worldwide, but bennettitalean foliage can be identified with certainty only in case the fossils are sufficiently well-preserved to show epidermal features. So far, the characteristic stomatal architecture of the group has never been systematically documented in these putative Paleozoic remains. Here, we present well-preserved bennettitalean leaves from Permian deposits in two widely separated regions of equatorial Pangea. Two species of cuticle-bearing leaf compressions from the late Permian Umm Irna Formation, Jordan, are here formally described as Pterophyllum pottii Bomfleur et Kerp sp. nov. and Nilssoniopteris jogiana Blomenkemper et Abu Hamad sp. nov. Moreover, bulk maceration of samples from the Umm Irna Formation yielded six additional types of dispersed bennettitalean cuticles that are here informally described. In addition, the Cisuralian (early Permian) uppermost part of the Upper Shihhotse Formation exposed at the Palougou section in Shanxi Province, China, has yielded the oldest unambiguous bennettitalean fossils known to date; they consist of fragments of entire-margined leaves with well-preserved cuticles that we assign to Nilssoniopteris shanxiensis Bäumer, Backer et Wang sp. nov. Unlike the characteristic puzzle-patterned cuticles typical of many Jurassic and Cretaceous bennettites, the cuticles of these Permian bennettitalean remains show non-sinuous anticlinal walls, greater variety in stomatal orientation, and rare occurrence of transversely divided subsidiary cells—features that have until now almost exclusively been documented from the hitherto oldest cuticle-bearing Triassic bennettitalean material. Finally, the taxonomic richness, disjunct distribution, and broad variety in macro- and micromorphological features in these Permian bennettitalean remains lead us to suspect that the origin of the group will date back still further in time, and might in fact coincide with very early occurrences of Bennettitales-like foliage from the Pennsylvanian and Cisuralian, such as Pterophyllum cottaeanum, P. eratum, or P. grandeuryi.

Comparative leaf micromorphology of Drypetes and Putranjiva (Putranjivaceae) and its taxonomic significance

Putranjivaceae are a pantropically distributed but poorly known glucosinulate-producing family of three genera (Drypetes, Putranjiva and Sibangea), previously included in Euphorbiaceae subfamily Phyllanthoideae. Characters of the leaf epidermis were previously suggested as being of infrafamilial taxonomic relevance, but epidermal features of the three genera have not so far been compared in the light of the phylogenetic relationships recovered by molecular data. Therefore, we compared the leaf micromorphology of 44 (out of c. 200) Drypetes spp. and two (out of three) Putranjiva spp. using light microscopy. Our findings revealed that there are more stomata types than previously reported in both genera. We also present a new record of stomatal complexes and epidermal cell characteristics. The cell wall ornamentation character on both surfaces of the epidermis is useful for distinguishing D. aframensis subsp. aframensis. Based on a combination of the studied characters, doubtful species of Drypetes and Putranjiva are recognizable as belonging to the two genera, and this will require taxonomic and nomenclatural adjustments. Other taxonomically useful characters are trichome distribution and types and leaf areole shape and tertiary veins branching patterns that appear to be relatively constant across the two genera. Oil droplets located within the cell lumen in Putranjiva differentiates it from Drypetes, where they inwardly streak the epidermal walls among other features. Thus, our study provides evidence that the investigated leaf micromorphological characters are useful for distinguishing the species of the two genera, and they corroborate the existing infrageneric classification of Drypetes that was based on exomorphology.

Taxonomic and Ecological Significance of Foliar Epidermal Characters in Four Taxa of Mussaenda L. (Rubiaceae) in Nigeria

Aims: This study investigated leaf epidermal features as taxonomic markers in delimiting two West African species (M. elegans and M. erythrophylla) and two Philippine infraspecific species (M. “Doña Aurora” and M.“Doña Luz”) of Mussaenda L. in Nigeria and their ecological significance. Study Design: The experiment adopted a Completely Block Design (CBD) of four plant taxa from two study locations with 10 replicates each, totaling 80 samples. Place and Duration of Study: The study was carried out in the Department of Plant Science and Biotechnology, University of Nigeria, Nsukka, between June and September, 2010. Methodology: Fresh leaves were collected from the Tropical Rainforest (TRF) and Derived Savanna (DS) vegetations of Nigeria under the same weather conditions. Leaf epidermal strips were prepared by clearing method, stained with Safranin and observed under the light microscope. Results: The stomata are of the paracytic type borne on polygonal to irregularly shaped, wavy epidermal cells. Simple trichomes were also a common feature in all taxa. Mussaenda erythrophylla has significantly (P ˂ 0.05) the least dense stomata (84.51 ± 0.73 mm-2) while M. “Doña Aurora” has the densest stomata (230.98 ± 2.67 mm-2). M. elegans and M. “Doña Aurora” have significantly the highest stomata index (28.48% and 28.98% respectively) while M. “Doña Luz” has the lowest (24.31%). Samples from the TRF have significantly higher density, index and size of stomata in M. elegans and M. “Doña Luz” than those from DS. Quantitative trichome parameters also vary among the taxa. The fewest trichomes were observed in M. elegans (7.90 ± 0.14 and 11.75 ± 0.21) while they are most abundant in M. “Doña Luz” (11.77 ± 0.11 and 18.90 ± 0.51). Ecological conditions affected these variables as trichomes were more abundant in the specimens collected from DS locations. Conclusion: Epidermal features are proven significant tools in taxonomic delimitation and as environmental indicators in predicting climatic changes and environmental pollution.