DOI: 10.5061/dryad.905qfttmq
title: Petiole anatomy of some species of Bauhinia L. sensu lato (Leguminosae Juss.) occurring in India

description: The petiole is a vital part of the leaf that acts as a bridge between the
 lamina and stem or branch for the transport of photosynthate, minerals,
 nutrients and provide flexible mechanical support to the lamina. Its
 anatomy remains unique and species-specific. Therefore, twelve species of
 Bauhinia sensu lato were investigated histologically in the present study.
 The disparities in the petiole outline, structure and composition of
 secondary xylem and presence of cell inclusions can be wisely employed for
 species identification. Conducting elements of the xylem and phloem were
 arranged as irregularly distributed individual vascular bundles in
 Schnella guianensis. Several vascular bundles joined to form a double ring
 of the xylem and phloem in Piliostigma foveolatum, P. malabaricum, P.
 racemosum, two species of Phanera (P. retusa, P. vahlii) and Bauhinia
 variegata while in the remaining species, it remained as a single ring.
 Other features of taxonomic importance are xylem ring that can be circular
 and complete and if incomplete crescent-shaped or “U” shaped, arrangement
 of cortical bundles and their position, accumulation of tannin etc.
 Deposition of tannin was observed in the pith, xylem and phloem parenchyma
 of Piliostigma foveolatum, P. malabaricum, Bauhinia tomentosa and B.
 variegata and in the pith and phloem parenchyma of Phanera phoenicea,
 Piliostigma racemosum and Phanera scandens. Tannin was found absent in B.
 acuminata and B. purpurea. All these features played important role in
 species recognition. Structural details of the petiole are described in
 detail for all the investigated species using standard anatomical methods
 and light microscopy. Findings revealed that anatomical characteristics of
 the petiole are of taxonomic value for this genus and can be valuable for
 species identification and classification.
description: <b><i>Collection of
 the plant materials</i></b><b>:</b> All the plant
 materials used in the study has been collected from the Maharaja Sayajirao
 University Campus, Waghai Botanical Garden (Gujarat state) and Botanical
 Garden of the Shivaji University, Kolhapur (Maharashtra State) except
 <i>Schnella guianensis </i>(Aubl.) Wunderlin. The details of
 voucher specimens are given in Table 1. Petiole of the fully-grown leaves
 (15 to 20<sup>th</sup> leaf from the apex) having similar age
 were collected from species of <i>Bauhinia </i>s.l. and fixed
 in FAA (Formalin - Acetic acid- Alcohol 10:5:85, v/v) (Berlyn and Miksche
 1976). For each species, 25 petioles (i.e., five petioles from five
 individuals each) from different populations were collected. All the
 species were either growing naturally in wild or they were under
 cultivation in the botanical garden of the Maharaja Sayajirao University
 of Baroda, Vadodara (Gujarat), Waghai Botanical Garden (Forest Department,
 Government of Gujarat) and the botanical garden of the Shivaji University,
 Kolhapur. After 24-36 hrs of fixation, they were transferred into 70%
 alcohol for further processing and storage. <b><i>Anatomical
 preparations</i></b><b>:</b> For the paraffin
 processing, the central portions of the petioles were cut into 2-3 mm long
 pieces and dehydrated through Tertiary Butyl Alcohol (TBA) series and
 processed by the routine method of paraffin embedding (Johansen
 1940). Central portions of the petiole from the fully grown and mature
 leaves were utilised for histological investigations. Serial transverse
 and tangential longitudinal sections of 10-15 µm thick were obtained using
 the rotary (Leica RM 2035) microtome. The sections were stained with
 safranin Astra blue combination (Srebotnik and Messener 1994). After
 passing through the ethanol xylene series, they were mounted in Dibutyl
 Phthalate Xylene (DPX). Sections were observed under Leica (DM 2000)
 trinocular research microscope and micro-photographs for important results
 were taken with Leica DFC 295 firewire digital camera.