BENTHAM AND HOOKER’S CLASSIFICATION Genera Plantarum (1862-1883) Prof. B. Ravi Prasad Rao Department of Botany Sri Krishnadevaraya Univversity Ananthapuramu 515003 A.P. E mail: [email protected] History of Plant classification • Period of Ancients: to ca. 1500 AD • Period of Herbalists: 1500-ca. 1580 • Period of Mechanical Systems: 1580-ca. 1760 • Period of Natural Systems: 1760 to ca. 1880 • Period of Phylogenetic Systems: 1880 to date. George Bentham (22 September 1800 – 10 September 1884) • George Bentham (England) was an amateur botanist until almost middle age, after which time he gave the subject of systematic botany all his attention. • He is the most critical, and analytical systematist, besides an accomplished linguist and Latinist. • Prior to his joint publication G‘ enera Plantarum’ with J.D. Hooker Bentham published world monographs of the families Labiatae, Ericaceae, Polemoniaceae, Scrophulariaceae and Polygonaceae. • He was the author of the 7-volume Flora of Australia . Sir Joseph Dalton Hooker (30 June 1817 – 10 December 1911) • Sir Hooker, a plant explorer and a plant geographer. • He collected plants from Himalayas, Lebanon, Antarctic and Atlas mountains. • He succeeded his father as Director of Royal Botanical Gardens, Kew. • Joseph Dalton Hooker published Flora of British India (1872-1897)S, tudent’s Flora of British Isles (1870) and also revised later editions oHfa ndbook of British Flora . • He also supervised the publication of Index Kewensis. George Bentham Joseph Dalton Hooker • Bentham and Hooker published their 3 volume work Genera Plantarum in Latin, at intervals between 1862 and 1883. • This work comprised the names and descriptions of all genera of seed plants then known and follow the classification principles of de Candolle. • Every genus was studied a new from the plant material of British and continental herbaria. • Full and complete descriptions were prepared from studies and dissections of the plants and not a mere compilation from literature. • Bentham and Hooker divided all seed plants into 3 classes, 3 subclasses, 21 series, 25 cohorts and 202 orders (= families). • Originally it was designed to include 200 orders and each order was given a definite number. Orders Vochysiaceae and the Cyrilleae were added later and included as 20a and 46a respectively. • The seed plants were considered by them to number about 97,205 species Orders Genera Species (Families) (Estimated) Dicotyledons Polypetalae 84 2,610 31,874 Gamopetalae 45 2,619 34,556 Monochlamydae 36 801 11, 784 Gymnospermae 3 44 415 Monocotyledons 34 1,495 18,516 Total 202 7,569 97, 205 • Bentham and Hooker’s system is Post-Darwinian in chronology but Pre-Darwinian in concept. • Publication of Darwin’s theories of evolution and Origin of Species coincided with the time of production of the first volume of Bentham and Hooker’Gs enera Pantarum . • J.D. Hooker although favoured a complete reorganization of their classification, Bentham did not accept the essentials of Darwin’s work, although he did so about a decade later. • This system was accepted throughout the British Empire and in the United States and was adopted to a lesser extent by some continental botanists. Now most of the world herbaria are following APG Classification. • In many of the Indian herbaria, specimens have been arranged according to Bentham and Hooker’s system. Class I. Dicotyledons 1. Cotyledons two 2. Tap root system 3. Reticulate venation 4. Perianth usually penta- or tetra-merous. Three subclasses: Polypetalae, Gamopetalae Monochlamydeae. Subclass (1) Polypetalae (Perianth dichlamydeous, heterochlamydeous, petals free). Three Series: Thalamiflorae Disciflorae Calyciflorae THALAMIFLORAE Sepals, Petals and Stamens all attached to receptacle. Six orders Ranales Parietales Polygalineae Caryophyllinae Guttiferales Malvales Ranales: Gynoecium apocarpous Families (8): RANUNCULACEAE DILLENIACEAE CALYCANTHACEAE MAGNOLIACEAE ANNONACEAE MENISPERMACEAE BERBERIDACEAE NYMPHAECEAE. DISCIFLORAE Ovary superior, immersed in disk of flower. Four orders. Geraniales- E.g. Geraniaceae Olacales- E.g. Olacaceae Celastrales- E.g. Celastraceae Sapindales- E.g. Sapindaceae E.g.: Geraniales – Ovule pendulous, raphae ventral. Families: 11 LINACEAE HUMIRIACEAE MALPIGHIACEAE ZYGOPHYLLACEAE GERANIACEAE RUTACEAE SIMAROUBACEAE OCHNACEAE BURSERACEAE MELIACEAE DICHAPETALACEAE. CALYCIFLORAE – Stamens fused to Calyx of flower. Five orders. Rosales-Rosaceae Myrtales-Myrtaceae Passiflorales-Cucurbitaceae Ficoidales-Aizoaceae Umbellales-Apiaceae E.g. Order: Rosales-9 families CONNARACEAE LEGUMINOSAE ROSACEAE SAXIFRAGACEAE CRASSULACEAE DROSERACEAE HAMAMELIDACEAE BRUNIACEAE HALORAGACEAE Subclass (2) Gamopetalae (Perianth dichlamydeous, heterochlamydeous, petals fused). Three Series: Inferae Heteromerae Bicarpellatae Series : INFERAE Ovary inferior; stamen number equals petal number 3 orders Rubiales- Rubiaceae Asterales- Asteraceae Campanulales- Campanulaceae E.g. : Rubiales – Stamens epipetalous; locules 2-many; ovules 1-many. 2 families CAPRIFOLIACEAE RUBIACEAE Series: HETEROMERAE Ovary superior; stamens opposite petals or double the petal number. 3 orders Ericales- Ericaceae Primulales- Primulaceae Ebenales-Ebenaceae E.g. : Order, Ericales – Stamens double petal no.; Ovary 2-many locules Five Families: ERICACEAE CLETHRACEAE; EPACRIDACEAE DIAPENSIACEAE LENNOACEAE Series: BICARPELLATAE Ovary superior, with 2 carpels. Four orders a) Gentianales – Corolla regular; leaves opposite. OLEACEAE SALVADORACEAE APOCYNACEAE ASCLEPIADACEAE LOGANIACEAE GENTIANACEAE b) Polemoniales – Corolla regular; leaves alternate. POLEMONIACEAE HYDROPHYLLACEAE BORAGINACEAE CONVOLVULACEAE SOLANACEAE c) Personales – Corolla irregular to oblique; ovules many in each locule. SCROPHULARIACEAE GLOBULARIACEAE LENTIBULARIACEAE GESNERIACEAE BIGNONIACEAE PEDALIACEAE ACANTHACEAE d) Lamiales – Corolla irregular to oblique; 1-2 ovules in each locule MYOPORACEAE VERBENACEAE LABIATAE (=LAMIACEAE) PLANTAGINACEAE Subclass (3) Monochlamydeae (Perianth monochlamydeous, homochlamydeous) No orders. Seven Series. Curvembryae- e.g. Nyctaginaceae Multiovulatae Aquaticae- Podostemonaceae Multiovulatae terrestris- e.g. Nepenthaceae Micrembryeae- e.g. Piperaceae Daphnales- e.g. Laurinae Achlamydosporae- e.g. Loranthaceae Unisexuales- Euphorbiaceae MONOCOTYLEDONS 1. Cotyledons One 2. Adventitious root system 3. Parallel venation 4. Perianth usually trimerous. No orders. Seven series. 1. Microspermae- e.g. Orchidaceae 2. Epigynae- e.g. Amaryllidaceae 3. Coronarieae- e.g. Liliaceae 4. Calycineae- e.g. Palmae 5. Nudiflorae- e.g. Aroideae 6. Apocarpae- e.g. Alismataceae 7. Glumaceae- e.g. Gramineae Merits 1.Full and complete descriptions of families and genera were made original dissections of plants and did not represent just a compilation from literature. 2.The system has great practical value for identification of plants. Keys to identify taxa are very useful for routine identification 3.Larger genera have been divided into subgenera to facilitate identification. 4.Treatment of certain families are correct. E.g. Leguminosae (=Fabaceae) is treated as single family - the latest APGC, 2016 also supported the same). Demerits 1. Placement of Gymnosperms between Dicotyledons and Monocotyledons. 2. The Monochlamydeae is an unnatura l assemblage of families 3. Placing the families with single whorl of perianth and without perianth at in monochlamydae is an anomaly. 4. Some polypetalous families are gamopetalous (e.g. Cucurbitaceae). 5. Liliaceae and Amaryllidaceae kept in different series on the basis of ovary nature (superior /inferior) although they show similarities. 5. No orders in Monochlamydeae and Monocots. 6. Although the system was proposed after Darwin’s theory of Evolution, the system has not followed any phylogenetic principles 7. Unisexuales comprise diverse families, but share only one major character, i.e., unisexual flowers. .