Vegetatio vol. 38, 3:157 164, 1978

AUTOMATIC CLASSIFICATION OF PHYTOSOCIOLOGICAL DATA ON THE BASIS OF SPECIES GROUPS*' *=

W. HOLZNER 1, M.J.A. WERGER 2 & G.A. ELLENBROEK 2.**

1) Botanisches Institut, Universitfit ftir Bodenkultur, Gregor Mendel Str. 33, A-1180 Wien, Austria. 2) Division of Geobotany, University of Nijmegen, Toernooiveld, Nijmegen, The Netherlands.

Introduction

In phytosociological tables species and relevds are ordered in such a way that the species with a more or less similar distribution pattern over the relev6s are grouped together and, similarly, releves with a more or less similar species content are placed next to one another. As stated previ- ously (Werger 1974a), membership of a species to a species-group is not necessarily determined by association with any individual species in that group, but can also be based on the restriction to the general distribution range in the table of a group of associated species. The same applies mutatis mutandis to the relevds belonging to a relev6 group (cf. Hull 1964-65). In this way clusters of relev6s characterized by groups of differential species are easily spotted in the table (cf. Van der Maarel et al. 1978).

Obviously the groups of species in a phytosociological table are not all fully differential, but mutual overlaps in occurrences between the species groups occur at various (hierarchical) levels and to various degrees. This makes it difficult to represent the floristic (and sociological) rela- tionships in a phytosociological table: in case all species groups would be mutually exclusive (or fully differential), or if one species group would only overlap with one other species group, a simple diagonal structure of the phyto- sociological table would adequately represent the pattern

* Nomenclature of species follows usage in Werger (1973). ** Contribution from the International Working Group on Data Processing in Phytosociology. Part of this paper is based on an unpublished lecture presented at the Prague meeting of the Working Group (Stockinger & Holzner 1973b). Copies of that manuscript and of a description of the mathematical background of the method (Stockinger & Holzner 1973a) are available from the first author. The computer program can be studied at Vienna, Nijmegen, and at the C.S.I.R.O., St. Lucia Qld., Australia (Dr. M. B. Dale). *** Supported by a grant from the 'Fonds zur F6rderung der wissenschaftlichen Forschung', Austria.

in species and relevds in the data set comprised in the table. Since mutual overlap between all species groups commonly occurs, however, not every species group can be represented in a single, coherent cluster in the phytosociological table, and consequently the diagonal structure of the table is distorted. With (automatic) classification this may prevent presentation of the data in an easily perceptible way.

An illustration of this problem is given in Fig. 1 for six differential species groups (a-f) of equal importance, which are mutually overlapping in distribution over the relev~s. It is thus impossible to arrange this type of vegetation data objectively in a phytosociological table which closely resembles the classic phytosociological table structure, and it is therefore impossible to computerize the procedures to arrive at such a table. When phytosociologists nevertheless succeed in presenting a phytosociological table with an easily interpretable structure, it is because they subjectively overemphasize the importance of some species groups and present them in the table as coherent species/relev6 clusters. This approach is justified and facilitated because of the species groups distinguishable in vegetation data gathered in nature not being all of equal importance. Furthermore, the interpretability, the usual wide extrapolation possibili- ties, as well as the consistency of the phytosociological table structure when new vegetation data are added to,it, indicate the appropriateness of the approach (cf. Whittaker

1962, Westhoff & van der Maarel 1973, Werger 1974b). It would, however, nevertheless be of significant value

to phytosociologists if a comparable table structure could be obtained by automatic procedures.

Possibilities for automatization

When only small segments of a phytosociological table are studied the difficulties outlined in the introduction do not occur. In such sufficiently small segments (e.g. comprising

157

relev~s

Fig . . Table :display of phytosociological data with six differ- ential sp&ies groups (~f) of equal importance and mutually overlapping in distribution over the relev6s.

only the species groups a and b in Fig. l) the differential species groups can be presented in single coherent clusters. It is possible to develop a model which is, based on the selection of such sufficiently small table segments and allows the presentation of floristic relationships in a phytosociological table of a more or less 'classic' structure along generally definable rules. The mathematical back-

ground of such a model was discussed in detail by Stockin-

ger & Holzner (1973a).

© e

~ f

The r-spot

In this model all sociological relevant species groups in a data file are determined and each group is located in a 'representative spot' (or r-spot). All species occurring in the

relevds defined by a sociological species group, but not belonging to that group, are omitted from the relevds, and for each relev6 a value r is calculated which indicates the strength of the species group still present in that relev6;

r(x, a) = n ~ d(s, a) S e X

in which n = the number of scores ~ 0 of species of group

x in relev6 a, and d (s, a) = score value of species s in relev6 a. The relevbs characterized by species group x are ordered within their r-spot according to their r value

(Fig. 2).

The essential species 9roups

Stockinger & Holzner (1973a) defined a grouping coeffi- cient 9 for species, which allows for a comparison of species

158

Species Relev6s

HELODO 2-2 2 2 - 2 2 2 3 2 2 2 - -

MYRAFR -333222-343322234236323-- RHUDIV - - 2 4 2 - - 2 224244

PENSET 12--22-22434 HELNUD 2--2222--2-2322222 2 3 3 - - HYPAET 1-2 ~ 2 - - 2 2 2 2 - -

CYMVAL d 5 4 3 4 - - CARSPI 3 2 2 2 2 3 2 - - RHUDEN - - 3 3 - - 2 2 - 3 2 4 3 2 2 4 KOECRI - - 2 2 2 2 - - 2 2 3 3 2 - -

Fig.2. An r-spot defined by species and relev6s. The relev6s are ordered according to their r-value which increases from left to right.

of different sizes with one another. The 9 value for each group forms a natural threshold for the 9 values of the smaller partial groups contained in it. Thus, a species group can be disregarded for presentation in a r-spot if

there is a larger group that contains the smaller group and has a higher 9 value. Only those species groups which are

not contained in another species group with a higher g value, are used for further analyses. Such species groups

are called essential species groups. Thus, the essential species group is sociologically

significant just because it is a group of species that is not contained in any other larger and more strongly tied species group. Consequently, all essential species groups together should, in dependence of the choice of the

critical value for the grouping coefficient 9, adequately and fully describe the sociological structure of the data file.

Often the large sociologicaly relevant groups will contain partial groups which are especially important or interesting for a more detailed sociological interpretation. Such a partition whithin groups can occur at several hierarchical levels. A presentation of all species in disjoint clusters is therefore appropriate for a tabular presentation of the phytosociologicat pattern only in special cases. The larger

the data set and the variation contained in it, the smaller the chances are that all species can be presented in disjoint

clusters.

The diagonal table

For each species there is at least one essential species group in which the species is represented, and each essential species group can be located in a r-spot. Thus, it is possible

Fig. 3. Diagonal table. The essential species groups are located on the diagonal and sociological relationships between them are indicated by spots away from the diagonal.

to construct a complete phytosociological table: vertically

the essential species groups are ordered and horizontally the relev~s belonging to the essential species groups. Such a

table contains the essential species groups diagonally from upper left to lower right (Fig. 3). The r-spots of the essen- tial species groups indicate the extent and importance of the clusters whilst the sociological relationships between the

essential species groups are indicated by the spots which have been formed away from the diagonal.

In this way an automatic tabulation based on 9 and r functions, is possible for each data file. However, within the essential species groups species and relev6s are not repeat- ed, and only those disjoint clusters which are situated on

the diagonal are certain. In practice such diagonally arranged tables based on all essential species groups are far too large. Therefore it is useful to choose some (optimat-

ed) essential groups for presentation of the sociological structure by means of objective criteria. This choice, based on approximation procedures, leads to an optimalization of the table structure in that the diagonally arranged

optimated essential species groups present an overview over the most important sociological relationships present in the data file. By deleting repeated occurrences of species and relev+s in this table a structure comparable to a 'classic' phytosociological table is obtained.

Alternatively, the results of the clustering procedure also

can be displayed by plexuses (cf. McIntosh 1973) which contain more information on the relations between the

species in one group than a table display does (Stockinger & Holzner 1972).

An example

To test the performance of the program in its selection of essential species groups, vegetation data of scrub, dwarf scrub, grassland and riverine forest formations of the Upper Orange River area, South Africa, were used. This data file consists of 56.0 relev6s containing 345 species occurring more than once in the relev6s. The data have

been collected according to the Braun-Blanquet approach. They have been analysed in a 'classical' phytosociological manner by Werger (1973), who classified the vegetation

into seven major groupings. Syntaxonomically the group- ings are different from one another at the rank of class. Several vegetation units of subordinate rank were distin- guished as well (see Table 1). The results of the computer analyses are compared with the interpretation given by Werger (1973).

All seven major groupings are distinguished by the com- puter program, but details are recognized with different degrees of success. The species groups are presented in plexuses (cf. Mclntosh 1973).

In one large plexus (Fig. 4) with # values between 0.745 and 0.494, sixteen species are grouped which together characterize the Diospyrion lycioidis, and in particular the

Rhoo-Diospyretum. In one partial group the two most common species in one subassociation are grouped with four of the five most common species characteristic for the Rhoo-Diospyretum. The other partial group mainly con- sists of all species characteristic for the alliance plus a few Rhoo-Diospyretwn species which are also comprised in the other partial group.

vLYCAREt/~" ~

aCELAFR v HASP

aRHUPYR

aMELDEC

vATRSEM vCLEBRA aRHUPYR ACAKA aRUBCOR

vDIOLYC aBROWIL

vCHEMUR

aBROWIL ( ~

SISBUR aCINLOB

0.8

-0.7

-0.6

Fig. 4. Diospyrion lycioidis plexus. The scale indicates the 9 values at which fusions occur. The horizontal arrangement of the clusters has no meaning. The numbers refer to the number of species contained in each cluster. The names of the species added to each cluster are abbreviated (capitals) and can be retrieved from Appendix 1. The indicator value of the species in the classification by Werger (1973) is shown as follows: a. character or differential species of an association; v. character or differential species of an alliance; o. character species of an order; k. character species of a class.

159

Table 1. Phytosociological classification according to Werger (1973).

I Diospyrion lycioidis: 1. Rhoo-Diospyretum (with 2 subassociations) 2. Zizipho-Acacietum karroo

1I Three grassland communities (not hierarchically classified).

III Pentzio-Chrysocomion: 1. Hermannio-Nestleretuat (with 3 subassociations)

IV Stipaorostion: 1. Enneapogono-Stipagrostietum (with 2 subassociations)

V Rhoetea erosae Grewio-Rhoetalia

lndigofero-Rhoion : 1. Rhamno-Rhoetum 2. Rhoo-Aloetum

Blepharido-Rhoetum Rhoetalia k:iliato-erosae

Hibisco-Rhoion : 1. Osteospermetum (with 2 subassociations) ~2, Stachyo-Rhoetum (with 2 subassociations) 3, Nanantho-Rhoeturn

Mayteno-Oleetum (with 2 subassociations) Setario-Buddleietum

VI Pentzietea incanae Pentzio-Rhioozetalia

Enneapogono-Rhigozion : 1. Zizipho-Rhigozetum (with 2 subassociations) 2. Melhanio-Hermannietum

Zygophyllion : 1. Monechmatetum (with 2 subassociations) 2. Nestlero-Pteronietum (with 2 subassociations)

Eriocephalo-Eberlanzietwn

VII Lycium prunus-spinosa community

Another independent species grouping contains the two most important character species of the Zizipho-Acacietum, Ziziphus mucronata and Setaria verticillata, fusing at g = 0.742, together with the always abundant species Acacia karroo at g = 0.667. This group remains separated from the plexus of Fig. 4, but in the diagonal table its relation to the Diospyrion lycioidis will be immediately apparent.

Two of the three grassland communities distinguished by Werger (1973) are described by the species group of Fig. 5. The plexus shows that the two communities are clearly separated in different parts of the configuration and connected through a number of shared species. The fusions in the cluster are between-g = 0.760 and g = 0.487. The third community is not distinguished by the program by its own species group, which was to be expected; that com- munity has no distinct species group but consists of a transition from grassland to karroid dwarf scrub with a typical species mixture.

The Pentzto-Chrysocomion is less clearly distinguished in four fusions between g = 0.504 and 9 = 0.434 in which Walafrida saxatilis, Pentzia 9lobosa, Tragus koelerioides, Chrysocoma tenuifolia and Nenax microphylla are subse- quently grouped. All these species, except the latter, are typical for the alliance but not specific for the association. Nenax microphylla occurs more typically on sites With very

160

shallow soils. The recognition of the Pentzio-Chrysocomion in the diagonal table on the basis of this species group is rather difficult since these are the species which intrude widely into the contact communities of the Pentzio- Chrysocomion (Werger 1973). These species also dominate in the Pentzio-Chrysocomion, however, and the charac- teristic species of the Hermannio-Nestleretum are not very abundant and/or constant. It is therefore no surprise that the association species group has not been recognized by the programme.

0,B

I HELCAE~ 2 E R A P L A ~ 3 ERACAP / ~ 1 HELRUG 2 WALDEN I ERARAC

ERAGUM 2

3 SETFLA ERARAC I

ERACAP 3 ~ T A U R ? 0.6 SUTAUR

IDICAN0

0.5

3 ERACUR 1 BRASER 3 HELDRE 1 CYMEXC

I NAPSCA

OA

Fig. 5. Plexus of grassland communities. For explanation see Fig. 4. 1. differential species of community 1; 2. differential species of community 2; 3. species common to communities 1 and 2.

The Stipagrostion is readily distinguished by the fusion of Stipagrostis obtusa, S. ciliata and Pentzia calcarea at g = 0.586 and joined by Plinthus cryptocarpus at g = 0.517. Another small species group-delineates one sub- association of the Pentzio-Stipagrostietum. The differences between the two associations in the alliance are expressed by their species combinations and not by exclusive species. Therefore, these communities do not have different r-spots on the diagonal.

Thirteen species groups indicate various units of the Rhoetea erosae. Some of these species groups are very small, however, and are not always readily interpretable. The Rhamno-Rhoetum and with it the order Grewio- Rhoetalia (and the alliance) is strongly characterized by a large species group (Fig. 6). Twenty-one species charac- teristic of the association are combined in this plexus with nine species thought by Werger (1973) to be more typical of

the alliance or order. The fusions lie between g = 0.853 and 9 = 0.546. Another small group of species clearly charac- terizes the Blepharido-Rhoetum. The Rhoo-Aloetum seems

only weakly be distinguished in another small species group with Aloeferox as the only characteristic species ot the association.

aHELLON ~HERQUA(

oBERDIS vOSYLAN aPEL~UA vCLUPUL vSUTKRA

0.9

"0.8

~0.7

0.6

05

Fig. 6. Grewio-Rhoetalia plexus. For explanation see Fig. 4.

Twenty-nine species characteristic of the class, four of the order Rhoetalia ciliato-erosae and one other species are combined in a single group with 9-values between 0.653 and 0.379 (Fig. 7). Other groups characterize subunits. The group of order species is overwhelmed by the class species and is thus not separately distinguished. The Hibiseo- ~hoion is characterized by a small species group at g =

0.533 to g = 0.456 and contains Hibiscus marlothtanus, Nenax microphylla, Aptosimum depressum, Blepharis vil- losa and Osteospermum leptolobum. Two other small species groups characterize the Osteospermetum (Erioce- phalus spinescens, Phymaspermum parvifolium, Osteo- ~permum leptolobum and Hibiscus marlothianus; g-values between 0.427 and 0.415) and the Setario-Buddleietum (Buddleia saligna, Setaria lindenbergiana, Solanum retro- flexum, Boophane disticha; g values between 0.851 and 0.556). However, the other associations have not been recognized by a distinct species group. Spots away from the diagonal in the table must identify them. There remain six small species groups consisting of a few Rhoetea species, but it is difficult to interpret their meaning in the light of Werger's (1973) classification.

The Pentzietea incanae are characterized by one large species group, which can be subdivided into two partial groups that seem to contrast the Enneapogono-Rhigozion against the Zygophyllion, or perhaps better, the Melhanio- Hermannietum against the Nestlero-Pteronietum (Fig. 8). The fusions occur between 9 = 0.785 and 9 = 0.313 though mainly above g = 0.5. Another small species group com- bines a few less constant Enneapogono-Rhigozion species.

The Lycium prunus-spinosa community is characterized clearly by a species group consisting of Drosanthemum sp., Zygophyllum incrustatum, Lycium prunus-spinosa, Salsola 9labrescens, Psilocaulon absimile, Chloris virgata and Tragus berteronianus, fusing in that sequence at 9-values between 0.690 and 0.371. Another smaller group con- taining partly the same species singles out one relev6 from this community.

It is thus apparent, that the major groupings are readily

identified by the computer program and characterized by species groups. Most, but not all, of the vegetation units of association rank are identified as well. Particularly some of those units which are not characterized by a strong group of characteristic species have not been identified by the program. Still, they are distinguished by Werger (1973) as associations, i.e. of equal rank and importance as other vegetation units possessing strong characteristic species groups (e.g. Mayteno-Oleetum, Nanantho-Rhoetum, Sta-

kHETCON kCHEHIR kHETCON kLANRUG kLIGALB kDIGERI kARIDIF kANTRIG kTHETRI kTARCAM kERACUR kHERCUN kERACUR kHIBPUS kTARCAM oRHUCIL kHERCUN kSELALB oSUTHAL kSELALB kCHEECK kHELDRE kLIGALB kCHEHIR oSUTHAL kANTRIG

Fig. 7. Rhoetea erosae (Rhoetalia ciliato-erosae) plexus. For explanation see Fig. 4.

0.7

-0.6

-0.5

0.4

0.3

161

vZYGGIL aPTE$OR

~ a N E S C A L

sSTICIL kPENINC( )vSTIOBT

kTHEHYS kENNBRA{~

aAPTSPI kPLIKAR

aBLEMIT aHERSPI

vENNCEH ARICUR

aALOCLA CHEALB ERAPOR

kPHASPI TRABER oRHITR[ aHERSPI kAPTMAR POLLEp kLIMAET aEBESPI aMICMAS sLESPAU LYCSAL aEUPAEQ

/" kPHASP[ oRHITRI RL[MAET vSERLOH OCENCIL

Fig. 8. Pentzietea incanae plexus. For explanation see Fig. 4.

.0.B

0.7

-0.6

0,5

oA

03

chyo-Rhoetum, Monechmatetum), These vegetation units will be difficult to identify in the diagonal table. Other vegetation units cannot be identified by a species group,

because they do not have such a group. They are typified by a characteristic combination of more widely spread species, i.e. by overlapping species groups (e.g. Zizipho- Rhigozetum, one of the grassland communities). The

program allows a fairly easy recognition of these vegetation

units. However, this occurs on the basis of 'overlapping spots' away from the diagonal in the diagonal table.

Patterns of hierarchization are difficult to identify in the output of the present program, though in some cases these are clearly indicated again by 'overlapping spots'.

Conclusion

In conclusion we may say that although not all details discussed by Werger (1973) are revealed in the classification suggested by the computer program, it is a powerful tool for a rapid tabular ordering of a large data set. The program approximates the structure and phytosociological group- ings in the data set and it reveals phytosociological rela- tions which were also revealed in a detailed analysis of the

162

same data set by traditional means. However, in a tradi- tional analysis very many more (undefined) criteria are used, consciously or not, in the classification process (cf.

Kaplan 1964, Hull 1970, Holzner & Stockinger 1973,

Werger 1974b).

Summary

The structure of phytosociological relationships between

vegetation groupings as apparent from a classic phyto- sociological table is briefly explained and a method to describe this structure by a table method and by means of automatic data processing is outlined. It is based on a

mathematical model using continuous clusters of species and arranging them in a diagonal table. This could replace the classical table work, The method is tested on a large

South African data set, which has been previously classified and interpreted. It appears that the method seems to be an efficient tool in rapidly ordering large phytosociological data sets revealing a table structure which approximates the classification arrived at in the traditional manner.

References

Holzner, W. & Stockinger, F. 1973. Der Einsatz von Elektronen- rechnern bei der pflanzensoziologischen Tabellenarbeit. Osterr. Bot. Z. : 121: 303-309.

Hull, D.L. 1964-65. The effect of essentialism on taxonomy. Two thousand years of stasis. I+II . Brit. J. Phil. Sci. 15: 314-326. ibid. 16:1 18.

Hull, D.L. 1970. Contemporary systematic philosophies. Ann. Rev. Ecol. Syst. 1: 19-54.

Kaplan, A. 1964. The conduct of inquiry. Chandler, San Francisco.

Maarel, E. van der, J.G.M. Janssen & J.W.M. Louppen. 1978. TABORD, a program for structuring phytosociological tables. Vegetatio 38:143 156.

McIntosh, R.P. 1973. Matrix and plexus techniques. In: R.H. Whittaker (ed.), Ordination and classification of communi- ties. Handb. Veg. Sc. 5: 157-191. Junk, The Hague.

Stockinger, F.J. & Holzner, W. 1972. Rationelle Methode zur Auswertung pflanzensoziologischer Aufnahmen mittels Elek- tronenrechner. In: E. van der Maarel & R. Tiixen (eds.), Grundfragen und Methoden in der Pflanzensoziologie, pp. 239-248. Junk, The Hague.

Stockinger, F.J. & Holzner, W. 1973a. Prinzipien einer Imple- mentierung des pflanzensoziologischen Zerlegungsproblems. Mitt. Bot. Arbeitsgem. Ober6sterr. Landesmus. Linz 4: 87- 106.

Stockinger, F.J. & Holzner, W. 1973b. Grundlegende Fragen bei der Verwendung yon EDV in der Pflanzensoziologie.

Symposium International Working Group for Data Pro- cessing in Phytosociology, Prague (manuscript).

Werger, M.J.A. 1973. Phytosociology of the Upper Orange River Valley, South Africa. V & R, Pretoria (Thesis Nij- megen).

Werger, M.J.A, 1974a. On concepts and techniques applied in the Zfirich- Montpellier method of vegetation survey. Bothalia 11 : 309-323.

Werger, M.J.A. 1974b. The place of the Zfirich-Montpellier method in vegetation science. Folia GeoboL Phytotax. 9: 99- 109.

Westhoff, V. & E. van tier Maarel. 1973. The Braun-Blanquet approach. In: R.H, Whittaker (ed.), Ordination and classi- fication of communities. Handb. Veg. Sc. 5: 619-726, Junk, The Hague.

Whittaker, R.H. 1962. Classification of natural communities. Bot. Rev. 28: 1-239.

Accepted 23 June 1978

Appendix 1. Species codes and species names of fig. 4-8

ABUAUS Abutilon austro-africanum ACAKAR Acacia karroo ACAMEL Acacia mellifera ACHASP Achyranthes aspera ADRRUP Adromischus rupicola ALOBRO Aloe broomii ALOCLA Aloe claviflora ANTRIG Anthospermum rigidum APTALB Aptosimum albomarginatum APTLEU Aptosimum Ieucorrhizum APTMAR Aptosimum marlothii APTSPI Aptosimum spinescens ARGLA~ Argyrolobium ianceolatum ARICUR Aristida curvata ARIDIF Aristida diffusa ASPDEN Asparagus denudatus ASPSET Asparagus setaceus ASTFIL Aster fillfolius ATRSEH Atriplex semibaccata BARLIC Barleria lichtensteiniana BARRIG Barleria rigida BERDIS Berkheya discolor BLEMIT Blepharis mitrata BOSALB Boscia albltrunca BRASER Brachiaria serrata BROWIL Bromus willdenowii CARSPI Carex spicato-paniculata CELAFR Celtis africana CENCIL Cenchrus c i l i a r i s CHEECK Cheilanthes eckloniana CHEHIR Cheilanthes hirta CHEALB Chenopodium album CHEMUR Chenopodium murale CINLOB Cineraria lobata CLEBRA Clematis brachiata CLILIN Cliffortia linearifolia CLUPUL Clutia pulchella COTDEC Cotyledon decus.-orbic, complex CYHEXC Cymbopogon exCavatus CYMPLU Cymbopogon plurinodls CYMVAL Cymbopogon validus

Appendix l. (continued)

CYPANG Cyphocarpha angus t i fo l i a DIABAS Oianthus basuticus DICANO Dicoma anomala DIGERI Digitaria eriantha DIOAUS Diospyros austro-africana DIOLYC Diospyros lycoides EBESPI Eberlanzia spinosa EHRRIG Ehretia rigida EHRERE Ehrharta erecta ENNBRA Enneapogon brachystachyus ENNCEN Enneapogon cenchroides ENNSCA Enneapogon scaber ENNSCO Enneapogon scoparius ERACAP Eragrostis capensis ERACUR Eragrostis curvula ERAGUM Eragrostis gummifiua ERAPLA Eragrostis plana ERAPOR Eragrostis porosa ERARAC Eragrostis raeemosa ERATRU Eragrostis truncata EUCCOR Euclea coriacea EUCCRI Euclea crispa EUPAEQ Euphorbia aequoris EUSPAS Eustachys paspaloides FINAFR Fingerhuthia africana GEIFIL Gelgeria filifolia GERPIL Gerbera piloselloides GREFLA Grewia flava HALLUC Halleria lucida HARFAL Harpechloa falx HAPSCA Haplocarpha scaposa HELCAE Helichrysum caespititium HELDRE Helichrysum dregeanum HELNUD He lichrysum nudifolium HELODO Helichrysum odoratissimum HELROS Helichrysum rosum HELRUG Helichrysum rugulosum HELLON Helictotrichon longifolium HERCUN Hermannia cuneifolla HERDEP Hermannia depressa HERPUV Hermannia pulverata HERQUA Hermannia quart in iana HERSPI Hermannia spinosa HETCON Heteropogon contortus HIBPUS Hibiscus pusillus HYPAET Hypericum aethiopicum INDSE$ lndigofera s e s s i l i f o l i a KIGAFR Kiggelar ia afr icana KOECRI Koeleria c r i s t a ta LANRUG Lantana rugosa LASCAP Lasiocorys capensis LESPAU Lessertia pauciflora L[GALB Lightfootra albens LIMAET Limeum aethiopicum LYCARE Lycium arenicolum LYCHIR Lycium hirsutum LYCSAL Lycium salinicolum MELREH Melhania rehmannii MELDEC Melica decumbens MICMAS Microloma massonii MYRAFR Myrsine africana NESKAL Nestlera humilis OLEAFR Olea africana ORYDEC Orygla decumbenu

163

Appendix 1. (continued)

OSYLAN Osyris ~anceolata PELCAL Pellaea calomelanos PELQUA Pellaea quadripinnata PENSET Pentaschistus setifo~ia PEN,ING Pentzia incana PHASPI Phaeoptilum spinosum PHYMAD Phvl]anthus maderaspatensis PLIKAR P1inthus karooicus POLLEP Polygala leptophylla PTESOR Pteronia sordida RHAPRI Rhamnus prrnoides RHIOBO Rhigozum obovatum RHITRI Rhigozum trichotomum RHUCIL Rhus ciliata RHUDEN Rhus dentata RHUDIV Rhus divaricata RHUERO Rhus erosa RHUPYR Rhus pyroides RHUUND Rhus undulata RHYTOT Rhynehosia totta RUBCOR Rubia cordifolia SELALB Selago albida SENLON Senecio longif]orus SETFLA Setaria flabellata SISBUR Sisymbrium burchelli SPOFIM Sporobolus fimbriatus STAAET Stachys aethiopica STICIL Stipagrostis ciliata STIOBT Stipagrostis obtusa

SUTAUR Sutera aurantiaca SUTHAL Sutera halimifolia SUTKRA Sutera kraussiana THETRI Themeda triandra THEHYS Thesium hystrix TRABER Tragus berteronianus TRIGRA Triehoneura grandiglumis VERCAP Vernonia capensis VISROT Viscum rotundifolium WALDEN Walafrida densiflora ZYGGIL Zygophyllum gilfillani

164