Stem anatomy of country bean
2003
Islam, M.T. (Bangladesh Agricultural Development Council, Dhaka (Bangladesh). Seed Distribution Div.) | Prodhan, A.K.M.A. | Bari, S.M.A. | Islam, M.O.
Anatomical investigation has been made on the stem of country bean (Lablab purpureus (L.) Sweet) at different stages of growth following the standard paraffin method of microtechnique. The epidermis is single layered with multicellular hairs and glandular trichomes. Beneath the epidermis there are 5-10 layers of cortical cells. The primary vascular tissue appears after the elongation of the first internode of the stem. The vascular bundles are collateral and arranged in a ring. There are two types of vascular bundles, large and small. There are one or more small vascular bundles in between two large bundles. The large vascular bundle contains xylem and phloem but small bundle may or may not contain both xylem and phloem. There are several poles of primary phloem outside the primary xylem. The pericycle is discontinuous. Two adjacent groups of sclerenchyma are connected by one or two layers of sclerenchymatous cells. The cambium initiates in the primary vascular bundle between xylem and phloem at the basal part of the stem of 4 days old plant. Gradually it extends towards the upper part. The cambium is at first confined to the fascicular region. Subsequently it extends into the interfascicular region forming a complete cambial ring. After the formation of the fascicular cambium it gives rise to the secondary xylem adaxially and secondary phloem abaxially. In the mature stem, most of the vessels are multiple, some are paired while the others are solitary. Most of the fibre cells in the phloem region are found in groups. The fibre cells are arranged in such a way that the structure looks like a pyramid. Tannin cells are present in the phloem region of younger and mature stem. The secretary cells devoid of tanniniferous contents have been observed in the secondary phloem region of the mature stem. The phellogen appears in the deeper cortex and produces periderm with lenticel. The periderm consists of 3-5 layers of cork cells abaxially and 2-3 layers of phelloderm adaxially.
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