FOLIAR EPIDERMAL STUDIES OF THE GENUS PTEROCARPUS JACQ. IN NIGERIA
ABTSRACT
A foliar anatomical study was carried out on four species of the genus Pterocarpus. Micro-morphological studies of characters of the leaflets specimen were carried out with the aid of light microscope. Qualitative microscope observation of character such anticlinical cell wall, pattern of stomata subsidary cells, trichome and ergarstic substance were observed and recorded. Macro-morphological characteristics of the Pterocarpus species studies showed that the epidermal cells were generally irregular with undulated to straight anticlinal walls on both surfaces. All the species were hypostomatic, the stomata are mainly paracytic and diacytic. The result also reflected in their growth habit in which the secondary venation patterns separate all four species with craspedodromous in P. erinaceus, cladodromous in P. mildbredii, semi-craspedrodomous in P. osun and mixed craspedodromous in P. santalinoides The dendogram generated from the morphometric analysis of the examined species grouped the four species into two main groups Pterocarpus santalinoides and P. mildbraedii as the first group, P. erinaceous and P. osun as the second group.
CHAPTER ONE
INTRODUCTION
Fabaceae is one of the largest families of angiosperm. The family includes 766 genera and about 19,500 species growing in a wide variety of different weather and habitat (Stevens, 2012). The family is known as the bean family or legume pea. They consist of perennial, annual plants trees and shrub which are identified with their fruits and compound, stipulate leaves (Stevens, 2012).The genus Pterocarpus Jacq is a tree species in the family Fabaceae which covers tropical regions of the hemispheres (Lavin, 2001).The scientific name is Latinized Ancient Greek which means “wing fruit”, referring to the uncommon shape of the seed pods in this genus (Lavin, 2001).The taxa compromises of around 60 species distributed round the tropics, twenty(20) of them in Africa (the plant list, 2013). Many of the trees branches spreads out, it also feels rough “pubescent to smooth “glabrous, most of the leaves are alternate, they are compound imparipinnate the stipulates of the species are small the stipules of the species are simple raceme, the raceme is terminal and sometimes axillary panicle they also have yellow-colored flowers where the bracteoles are small, the calyx are mostly incurved, obconical, 5-toothed; teeth short, upper 2 ± connate. the Corolla are papilionaceous, they are exerted beyond calyx; the petals are mostly extended and clawed; they are also standard ovate shape to orbicular in shape, as keel crisped on margin. Stamens are 10, mona delphous to dia delphous, the staminal sheath split open dorsally; anthers are versatile. Ovary are stipitate or sessile, 2–6- ovuled; style is incurved, filiform, glabrous; stigma is terminal. Legume indehiscent, orbicular, flattened, largely hardened winged around margin, usually 1-seeded; style continuous, incurved. Seeds oblong or sub reniform, hilum is small (the plant list, 2013).
Pterocarpus erinaceus Poir, also, called the rosewood is a vegetable tree of African savannas. Pterocarpus santalinoides Dc commonly referred to as red sandal wood in English (Ayman, 2013). (Uchegbu, and kwu, 2012) Pterocarpus osun Craib is a tree that sheds it leaves off at maturity, it is also leguminous native to African savannahs and dry forests it is one of the mostly distributed all over the world (Durugbo, 2013). P. osun usually yield valuable timber that is traded as padauk (Lavin, 2001).
1.1 Scientific classification of Pterocarpus
Kingdom – Plantae
Subkingdom – Tracheobionta
Super division -Spermtophyta
Division -Magnoliophyta
Class -Magnoliopsida
Subclass – Rosidae
Oder – Fabales
Family – Fabaceae
Genus – Pterocarpus
Species
Erinaceous Poir
mildbraedii Harms
osun Craib
santalinoides Dc
1.2 Distribution:
The species are native to Sierra Leone, Liberia, Côte d’Ivoire, Ghana, Benin, Nigeria, Cameroon, Equatorial Guinean and Gabon. Most of these species are seen in a clear dried forest of a semi-arid and sub humid land and yearly have rainfall between 600 to 1200mm with a normal to extended dry season that sometimes stay for long as 8 to 9 months with an annual temperature of the trees ranging from 15 to 32 ºC, these species can also tolerate extreme “high temperature of 40 ºC the trees length reaches up to 0 to 600m and can survive in a shallow soil they also accept drought and can survive annual dry season as well as the savanna bush fires and colonize follow lands. (Adetunji, 2007).
1.3 Statement of Problem
Gross morphological characters such as flowers and fruits are mostly used for classification and identification of Pterocarpus species. However, these characters are not always available on plants. Therefore, other structures of identifications such as micro-morphological study of stomata types and venation patterns of these species should be employed to further improve the taxonomic knowledge of the genus.
1.4 Aims and Objectives of the Research
This research work aims at conducting foliar anatomical study on the species of Pterocarpus in Nigeria with the following objectives
- To study the similarities and differences in morphological characteristics of the species of Pterocapus found in Nigeria.
- To describe in details each species considered
- To examine the venation pattern of the species
1.5 Justification of Research
The study is expected to add diagnostic anatomical and morphological characters that could aid identification and that could be used to resolve the circumscription of the species
FOLIAR EPIDERMAL STUDIES OF THE GENUS PTEROCARPUS JACQ. IN NIGERIA