A Field Guide to the Common Trees and Shrubs of Sri Lanka Mark S. Ashton, Savitri Gunatilleke, Neela de Zoysa, M.D. Dassanayake, Nimal Gunatilleke and Siril Wijesundera
WHTTublications (Pvt.) Limited 1997
To all our teachers for inspiring us to appreciate and enjoy nature
A Field Guide to the Common Trees and Shrubs of Sri Lanka (including an introduction to the flora, plant uses, and index). Ashton, Mark S.; Gunatilleke, Savitri; de Zoysa, Neela; Dassanayake, M.D.; Gunatilleke, Nimal and Wijesundera, Siril. Published by WHT Publication (Pvt.) Ltd for the Wildlife Heritage Trust of Sri Lanka, 95 Cotta Road, Colombo 8, Sri Lanka. © 1997—Mark S. Ashton, Savitri Gunatilleke, Neela de Zoysa, Nimal Gunatilleke, M.D. Dassanayake. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, without the prior permission in writing of the publisher. Within Sri Lanka exceptions are allowed in respect of fair dealing for the purpose of research or private study, or criticism or review as permitted under the Code of Intellectual Property Act (1980). Inquiries concerning reproduction outside these terms and in other countries should be addressed to the Managing Trustee, Wildlife Heritage Trust of Sri Lanka, 95 Cotta Road, Colombo 8, Sri Lanka.
Printed in Sri Lanka by Gunaratne Offset Limited. Typesetting and colour-separation by Iris Colour Graphics Limited, Colombo, Sri Lanka.
Contents Preface Acknowledgements
PART I: Introduction to the Flora Geography Landform Climate Geology Soils Vegetation types Trends in land use
1 2 4 6 7 9 12
PART II: The field guide An explanation of species and family descriptions Glossary Key to identification of tree families Descriptions of tree ferns Descriptions of cycads and gymnosperms Descriptions of monocotyledonous angiosperms Descriptions of dicotyledonous angiosperms
19 33 43 51 53 59 75
PART III: Plant uses Uses of trees in Sri Lankan history The use of medicinal plants in Sri Lanka
PART IV: Index Index of English names Index of Sinhala names Index of Tamil names Index of Scientific names
411 413 419 423
Preface The stimulus for The Field Guide to the common trees and shrubs of Sri Lanka was the success of a similar guide for Puerto Rico compiled by one of us (MA). Begun as a modest effort in 1985, it was boosted in 1988 with grants from the WWF-US and from the Environmental Program of the MacArthur Foundation. The collective inertia made this comprehensive end-product possible. This Guide is organized into three parts. The first part is a general introduction that deals with the geography, climate, geology, soils, natural vegetation and the history of landuse on the island. This section intends placing the tree and shrub species described in context with the biological and cultural history of the island. The second part is the main body of the Guide which includes 95 families and 704 species of trees and shrubs, each with its own illustration. It is preceded by a key to identification and with an explanation on how to refer to the descriptions. All of the technical terms used are listed in a glossary. The information is organized in a form accessible to the practical user as well as the more advanced botanical reader. The third part of the book is a reference to plant uses. It includes sections on timber, medicinal, as well as food and other uses of the trees and shrubs described. This section gives an overview to the general reader of the extent of traditional and contemporary uses of plants in this country and provides more precise information to the forester. It is hoped that this book will serve a long-felt need by making available information on the fascinating plant life of Sri Lanka to a wide range of people. It is a pioneer effort, and the authors would welcome suggestions and criticisms from those who use the book. We also hope that in the coming few years we can compile a sequel to this book on the less common and rare trees and shrubs of Sri Lanka.
Acknowledgements This work has been carried out over a period of eleven years somewhat intermittently by the authors in their spare time. It made it no less easy that they were scattered in several different places. We would like to thank the School of Forestry and Environmental Studies/ Yale University for the use of computer printing facilities. We also thank Magdon Jayasuriya, Curator, National Herbarium/ Peradeniya and D. B. Sumithraarachchi/ Director of the Royal Botanic Gardens/ Peradeniya for use of the herbarium and the helpful co-operation of the herbarium staff. We thank K. Vivekanandan, Chief Research Officer of the Forest Department/ Sri Lanka/ for use of the Department herbarium. We appreciate the important contributions made by Nishanta Rajakaruna by supervising and co-ordinating the guide during an important period and Jayantha Samarasinghe and Sunil Gamage by collating the plant-uses section. We also thank A. M. Gunapala for collection of plant specimens, and Milton Liyanage for the maps in the introduction. We especially thank those who contributed the most to the illustrations: Malini Goonatilleke/ L. S. B. Wadigamangawa/ Chaminda Nagahapitiya/ Sumedha Madawala/ A.S.T.B. Wijetunga/ Dharshini Goonatilleke and Jagath Kodituwakku. We also recognize the many others who helped with illustrations: Ruchindra Abeytunga/ Maitri Jansz/ Indula Silva/ Shanta Jayaweera; and the numerous students of the Botany Department at Peradeniya: N. Ekanayake/ C. de Silva/ N. de Silva/ K.D. Ratnayake/ D. Welagedara (Botany Special Part HI/ 1989); Nilanthi Herath, Nilmini Kanthi/ Champa Nalinie/ -Niranjala Perera, Hasantha Priyadharshani/ Sunil Sarath Kumara, Asanga Uduwela, Malkanthi Wijepala (Botany Special Part I/ 1990); Kamani Dambawinna/ Deepthi Dissanayake/ Priyani Kulatunga/ Rohini Padmalatha/ Renuka Premaratna/ Mohamud Rizvi/ Yojitha Seneviratne/ Kushan Tennakoon/ Dayani Tilakaratne/ Thusitha Weerasekara (Botany Special Part H/ 1990); Anoma Basnayake/ D. Ekanayake/ Anoma Perera/ Udeni Pushpalatha, Geethani Rathnayake/ Deepika Somaratne, Priyanka Weerasinghe/ Hemanthi Wijeratne/ Kapila Yakandawala (Botany Special Part IH/1990). Our appreciation is also extended to Mr Rohan Pethiyagoda for the encouragement given to us during preparation of the manuscript/ to Ruwan Herath and Miss Elita Atapattu for the long hours spent and their tireless efforts in typesetting the manuscript.
Introduction to the Flora Geography Landform Climate Geology Soils Vegetation types Trends in land use
1 2 4 6 7 9 12
ince ancient times Sri Lanka has been well known for its great natural beauty. A rich and diverse flora is one of the country's important'assets. This small island of 65/500 square kilometres has over 3,500 flowering plant species native to it. Over a quarter of these species are considered unique to the country. Today Sri Lanka is considered one of the most biodiverse areas in South Asia. Recent scientific evidence indicates that many of the plant species in the southwest of the country have a Deccan-Gondwana and ancestry.
The island's natural flora has been enriched by the ageold Lankan tradition of cultivating spice/ food/ ornamental/ and medicinal plants. Many of these were introduced from places as far off as China/ the Mediterranean/ Ethiopia/ and Arabia/ by travellers who visited the country during a period of at least two thousand years. The introduction of plantation crops such as tea and rubber during the 19th century has not only altered the landscape but the nation's economy as well. This rich plant heritage is better appreciated if seen in the natural and historical context of the country. We therefore briefly describe factors such as geology/ soils, climate and land form/ and landuse trends that have influenced and shaped the plant life of Sri Lanka. Geography Sri Lanka is situated close to the Figure 1. Geographical location of Sri Lanka with respect southeastern tip of India/ north to the tropical and subtropical regions of the world. of the equator (Fig. 1). The two. countries/ although separated by the shallow Palk Strait/ share the same continental plate and are linked by coral reefs and islets/ popularly known as Adam's Bridge. Both the evolutionary history and the cultural traditions associated with the flora of this country have a strong Indian influence (see Box 1). The nearest land masses, other than India, are the Malayan region towards the east and the African continent to the west.
BOX 1. The origin of Sri Lanka's natural plant communities has become clearer with recent evidence on the geological past of the Asian region. It has been traced back a hundred million years to the early Cretaceous period when the ancient southern continent Gondwana began breaking up. The Deccan plate, a fragment consisting of India and Sri Lanka, drifted north and collided with mainland Asia nearly 55 million years later. After a lapse of another 20 million years, in the late Miocene, Sri Lanka was separated with the submersion of the land area between the two countries. The maps below show the geological past of Sri Lanka and the time scale indicating the different epochs, periods and eras with time of their initiation in millions of years before present (MYBP). Map stages show the Deccan plate, wedged between Africa and Australia, as part of Gondwana (I); as the Deccan plate separates from remaining Gondwana (II); and the isolation of Sri Lanka from India with rising sea levels (III). IMPORTANT EVENTS
MIOCENE — ——
| QUATERNARY' I
Land form The present landform of Sri Lanka is the result of millions of years of weathering by rain and wind, as well as movements of the earth's crust. The topography of Sri Lanka is remarkably varied for its small area, with coastal plains, lowland hills and a mountainous interior (Fig. 2). This variation is reflected in the complexity of the island's diversity of natural plant communities and crops.
The coastal plains hardly exceed 100 m in elevation. The lowlands cover nearly three quarters of the country and are extensive in the north and east. Towards the south-central part/ the land rises gently to about 600 m in elevation with low/ rounded hills and crests of hard rock. Two large basins, the Kelani and Uva, characterize this area. The central mountain area consists of a complex of plateaux/ mountain chains and basins/ much of it reaching elevations greater than 1800 m. Along the southern margin of the highlands are numerous waterfalls which have led to the speculation that the mountains were formed by upliftment during relatively recent geological times. The central mountains are steeply dissected particularly on the south and southwestern faces. The highest part takes the shape of an anchor/ marked by Adams Peak/ Kirigalpoththa/ Pidurutalagala and Namunukula/ all major peaks reaching between 2000 m and 2524 m. These are interspersed with the plateaux of Horton Plains, Ambawela and Nuwara Eliya, To the northeast and southwest of the central mountains are two small massif s/ the Knuckles mountains and the Rakwana hills respectively (Fig. 2).
ALTITUDE IN METRES
1500 1000 500 100
Figure 2. Altitudirial variation within the island and The drainage pattern its highest peaks. of the country is almost entirely governed by the central highlands/ with all the perennial water courses originating in the mountains and winding their way down to the plains below (Fig. 3).
Sri Lanka's equatorial position gives its lowlands a tropical climate/ with year round temperatures of 27-28°C and a relatively constant day length. Rainfall is largely governed by monsoonal winds which occur during two seasons of the year. From mid-May to September/ the monsoon blows from the southwest direction and brings in a greater amount of moisture than during December to February when the wind blows from the northeast. The distinct intermonsoonal periods Area above ZOOm. receive convectional rains and at times cyclones. During the southwest monsoon/ the position and dramatic relief of the southwestern side of the central highlands forces the moistureladen air upwards. The rapidly cooled air condenses/ causing precipitation mostly on the windward slopes of the island's southwest. During this time the northeastern and southeastern parts of the land hardly receive any rain. On the other hand, the northeast monsoon winds rise over the central highlands more gradually/ and the rain shadow effect is not nearly so distinct/ allowing precipitation to fall on the entire island. This has resulted in the division of the country into two major climatic regions; Figure 3. TJie main rivers showing their origin in the the wet zone which remountains and direction of flow to the sea. ceives rain from both monsoons/ and the dry zone which receives rain from only one. The gradual change from the wet to dry zone allows an intermediate zone to exist. In addition/ two small areas at the exteme northwest and southeast of the country have a very dry climate and are known as arid zones (Fig. 4). Furthermore/ owing to the small size of the island and its 'open' position in the Indian ocean/ an oceanic climate dominates the coastal lowlands. This area
is strongly influenced by local convectional winds and their associated thunderstorms. These local sea winds sometimes influence the interior of the country often interacting with monsoonal winds. Besides rainfall, temperature plays an important role in highland regions. For every 100 m increase in elevation, the mean temperature falls by 0.5°C. On the plateaux there is often ground frost in the lower lying areas between December and March.
Rainfall by Season JA. North-Eost Monsoon
n Wet and Dry Months
A- Maha Illupalama Ppt
,RF curve undercuts temp, curve, representing a dry period
Black area = RF>100 mm
D-Nuwora Elrya pj!
RF curve RF