Svs(>-»ifl|jc Botany (19%). 21(4): pp 607-616 Copyright 1W by the American Society of Plant Taxonomi-t- Wood Anatomy of Akaniaceae and Bretschneideraceae: a Case of Near-identity and its Systematic Implications

SHERWIN CARLQUIST1 Santa Barbara Botanic Garden, 1212 Mission Canyon Road, Santa Barbara, California 93105 'Address for correspondence: 4539 Via Huerto, Santa Barbara, California 93110

Communicating Editor: David £. Ciannasi

ABSTRACT. Wood anatomy is described in detail for the single-species families Akaniaceae and Bretschneideraceae, placed close together in most phylogenetic systems. Both families have simple perfora­ tion plates with occasional scalariform plates, alternate lateral wall pitting, helical sculpturing on vessel walls, septate fibers with pits simple or nearly so, scanty vasicentric axial parenchyma, and wide tall multiseriate rays composed mostly of procumbent cells. Differences between the genera are relatively few and minor compared with resemblances; close relationship is indicated. Wood anatomy of the two families resembles that of Sabiaceae and, to a lesser extent, that of other Sapindales. The wood is distinctive within Capparales whether that order is defined traditionally or in the light of molecular studies. Wood data are compatible with an interpretation that Akaniaceae and Bretschneideraceae diverged from near the base of Sapindales.

The families Akaniaceae and Bretschneideraceae, glucosinolates, but no author has suggested that each with a single species, have been placed next to either Drypetes or Euphorbiaceae as a whole is close each other in Sapindales (including Rutales of some to the other glucosinolate families. The arrange­ authors) by Dahlgren (1980), Cronquist (1981), and ment of Dahlgren (1980) was altered on the basis of Thorne (1992); Takhtajan's (1987) treament includes molecular data by Gadek et al. (1992), Rodman et al. them in Sapindales with only a single family (1993), Rodman et al. (1994) and Conti et al. (1996), (Melianthaceae) intervening between them. The who find that a monophyletic clade is formed by families differ in that Akaniaceae have hypogynous the families Akaniaceae, Bataceae, Brassicaceae, flowers and are alleged to lack myrosin cells (which Bretschneideraceae, Capparaceae, Caricaceae, Gyr- are usually thought to contain glucosinolate com­ ostemonaceae, Koeberliniaceae, Limnanthaceae, pounds), whereas Bretschneideraceae have perigy- Moringaceae, Resedaceae, Tovariaceae, and Tro- nous flowers and myrosin cells (Cronquist 1981). paeolaceae. Outgroups relatively close to these Although Akania may lack myrosin cells, both glucosinolate families include Geraniales, Myrtales, families contain glucosinolates (Etlinger and Kjaer and Sapindales, according to the data of these 1968); some families that contain glucosinolates papers. apparently lack myrosin cells (Metcalfe and Chalk The intriguing redefinition of the glucosinolate 1950) but all possess some portion of this chemical families (which might tentatively still be termed syndrome. Recently, similarity in embryology be­ Capparales) by Rodman et al. (1993), Rodman et al. tween Akaniaceae and Bretschneideraceae has been (1994), and Conti et al. (1996) invites comparison of demonstrated (Tobe and Peng 1990; Tobe and their cladograms with data from wood anatomy. 1 Raven 1995). have examined wood of Bataceae (Carlquist 1978), The glucosinolate-bearing families, once scat­ Brassicaceae (Carlquist 1971), Gyrostemonaceae tered among seven orders (Batales, Capparales, (Carlquist 1978), Tovariaceae (Carlquist 1985), and Celastrales, Euphorbiales, Geraniales, Sapindales, Limnanthaceae and Tropaeolaceae (Carlquist and and Violales; Cronquist 1981), were included in an Donald 1996). Numerous papers contain data on expanded Capparales by Dahlgren (1980) on the wood anatomy of Capparaceae (see Gregory 1994). basis of certain character distributions and then by Wood descriptions have been furnished far. Koeber­ Rodman (1991a, b), on the basis of phenetics and liniaceae (Gibson 1979) and Salvadoraceae (den cladistics. Excluded from Dahlgren's (1980) revised Outer and van Veenendaal 1981). I plan papers on Capparales were the glucosinolate families Carica- wood anatomy of other glucosinolate families to ceae and Pentadiplandraceae (often placed in supplement this picture. Some information on Violales), as well as Bretschneideraceae (usually- wood anatomy has been offered for Akaniaceae by included in Sapindales). Drypetes, alone among Dadswell and Record (1936), Heimsch (1942), Ilic Euphorbiaceae, has been reported to possess (1991), and for Bretschneideraceae by Cheng (1980),

607 608 SYSTEMATIC BOTANY [Volume 21

Cheng et al. (1992), Heimsch (1942), Luo (1989), and (Carlquist 1978). A few radial sections of Tang (1935). The present account is offered as a way Bretschneidera sinensis wood were left unstained and of offering supplementary quantitative and qualita­ were examined with SEM. Macerations were tive data, using both light microscopy and scanning prepared with Jeffrey's Fluid and stained with electron microscopy (SEM). The material of safranin (Carlquist 1985). Bretschneidera studied by Heimsch (1942) was from Vessel diameter is measured as lumen diameter; a twig, and thus may represent juvenile wood an attempt is made to estimate the average expressions. By placing descriptions of the woods diameter of each vessel (e.g., the average between of Bretschneidera and Akania together, the idea that widest and narrowest diameter), since that average they are closely related, common to both traditional would be the most significant measurement with phylogenetic systems as well as those based on respect to conductive capacity of a vessel. Terms are molecular data (e.g., Rodman et al. 1994), can be according to the IAWA Committee on Nomencla­ assessed. ture (1964). The ray types of Kribs (1935) have been Data on wood anatomy are of particular interest accepted here. The term "imperforate tracheary because there are such diverse growth forms (trees, elements" is used in a wide sense, including the shrubs, stem succulents, annuals) among the range from tracheids to libriform fibers, because of glucosinolate families. The cladogram of Rodman the continuous nature of this range and because et al. (1994) places Tropaeolaceae basal to Akania- this usage is common among recent authors on ceae and Bretschneideraceae, thereby offering the wood anatomy. Scale bars in all Figs, represent 10 intriguing possibility, acknowledged by those au­ urn units. thors, that there may have been marked shifts in habit during the hypothesized divergence of the herbaceous family Tropaeolaceae from the arboreal RESULTS sister-families Akaniaceae and Bretschneideraceae. Akania bidwillii (Fig. 1-8). Growth rings incon­ The nature of wood anatomy of these families spicuous, most latewood vessels only slightly should be considered in connection with the narrower than earlywood vessels. Vessels solitary hypothesized shift in habit from herbaceous to or in small clusters or multiples (Fig. 1), mean woody hypothesized by Rodman et al. (1994). number of vessels per group = 1.74. Vessels Some degree of divergence of Akaniaceae and rounded in transectional outline. Vessels mostly Bretschneideraceae in wood anatomy would be with simple circular to elliptical perforation plates; expected because of the marked geographical a few perforation plates basically scalariform but separation of the two families. Akania bidwillii with numerous aberrations (interconnections be­ (Hogg) Mabb., formerly known as A. hillii Hook. f. tween bars) present (Fig. 3). Vessel to vessel pitting and A. lucens (F. Muell.) Airy-Shaw, is the sole alternate, pits about 5 urn in diameter (Fig. 5). species of Akaniaceae and is native to southeastern Inconspicuous grooves interconnecting pit aper­ Australia (Cronquist 1981). Bretschneidera sinensis tures (coalescent pit apertures) present on vessel Hemsl., the only species of Bretschneideraceae, walls (Fig. 5, below; Fig. 6). Vessel to axial occurs in China and Taiwan (Lu et al. 1986). parenchyma pitting (Fig. 8) and vessel to ray pitting scalariform or transitional. Mean vessel diameter, 82 um. Mean vessel wall thickness, 2.5 um. Mean MATERIALS AND METHODS number of vessels per mm2, 63. Mean vessel Wood samples were obtained from xylaria (wood element length, 730 um. Imperforate tracheary sample collections). The Forestry Commission of elements with very small inconspicuous borders New South Wales provided the samples of Akania (Fig. 7), the borders visible in face view and in bidwillii (SFCw-D10096). The Samuel J. Record transections. The imperforate tracheary elements collection of the U. S. Forest Products Laboratory- mostly septate one to three times each, and thus are supplied the wood samples of Bretschneidera sinen­ septate fibers. Mean wall thickness of septate fibers sis (SJRw-21841, 22016). Locality data for these length of septate fibers, 1488 um. Axial parenchyma samples were not available for these specimens scanty paratracheal (vasicentric) with a few termi­ other than their country of origin (Australia and nal cells at ends of growth rings. Axial parenchyma China, respectively). in strands of 4-8 (mostly 5) cells. Ray cells Sections were prepared on a sliding microtome multiseriate (Fig. 2), heterocellular, composed and stained with a safranin-fast green combination mostly of procumbent cells, with upright cells at 1996] CARLQUIST: AKANIACEAE AND BRETSCHNEIDERACEAE 609

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FlCS. 1-4. Wood sections of Akania bidwillii. 1. Transection; margin of growth ring across middle of photograph. 2. Tangential section; multiseriate rays tall, wide, uniseriate rays absent. 3. Aberrant scalariform perforation plate from radial section. 4. Transection, growth ring margin vertically down the middle of the photograph. Two rhomboidal crystals shown in the ray cells. Figs. 1-2, scale above Fig. 1; Fig. 3, scale above Fig. 3; Fig. 4, scale above Fig. 4; divisions in all scales = 10 urn. 610 SYSTEMATIC BOTANY [Volume 21

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FIGS. 5-8. Details of wood of Akania bidwillii. 5. Alternate vessel to vessel pitting from vessel in radial section; grooves interconnecting pit apertures evident as pale diagonal streaks between pits in lower half of photograph. 6. Portion of vessel wall from radial section to show diagonal grooves interconnecting pit apertures. 7. Pits on septate fibers from radial section; septa out of focus above right and below left. 8. Scalariform and transitional vessel to axial parenchyma pitting from radial section. Figs. 5-8, scale as in Fig. 3. 1996] CARLQUIST: AKAN1ACEAE AND BRETSCHNEIDERACEAE 611 the tips of rays and as sheathing cells on sides of pits of tangential walls of ray cells (Fig. 18, arrows). rays (Fig. 2, arrow). Ray cells radially shorter at Mean height of multiseriate rays, 1654 um. Mean margins of growth rings (Fig. 4, center). Ray cell width of multiseriate rays at widest point, 5.8 pm. wall thickness about 1.8 um. Pits in ray cells nearly Mean height of uniseriate rays, 173 pm. Wood all simple. Mean height of multiseriate rays, 2793 nonstoried. No crystals observed. Ray cells and um. Mean width of multiseriate rays at widest axial parenchyma cells with dark-staining contents point, 7.1 cells (range: 3-10). Wood nonstoried. (Figs. 10,11). Rhomboidal crystals are present singly in occa­ Heimsch is correct in saying that scalariform sional ray cells (Fig. 4, arrows). perforation plates are only occasional in Occasional perforation plates that are near- Bretschneidera, whereas the description of Tang scalariform in disposition of bars, grooves in vessel (1935) suggests that scalariform perforation plates walls, and crystals in ray cells are three features are characteristic in the species. Heimsch (1942) newly reported for Akania. In other respects, calls the imperforate tracheary elements (which he features in the above description are very similar to observed in twig material) fiber-tracheids, but I was those reported by Heimsch (1942). The ray type of unable to locate any borders on pits of imperforate Akania is not really referable to any of the ray types tracheary elements. Otherwise, my descriptions of Kribs (1935). Multiseriate rays are heterocellular agree with those of Heimsch (1942). Terminal with elongate tips and therefore correspond to parenchyma may not be present in the ordinary Heterogeneous Type IIA, but uniseriate rays are sense; it may be vasicentric parenchyma associated absent in Heterogeneous Type II of Kribs (1935). with the small latewood vessels. Borders on ray cell This condition has been reported in Sabiaceae pits of Bretschneidera are newly reported. (Carlquist et al. 1993).

Bretschneidera sinensis (SJRxv-22016) (Figs. DISCUSSION 9-18). Wood with inconspicuous growth rings (Figs. 9, 11). Latewood vessels slightly narrower Resemblances Between Woods of Akania and than earlywood vessels (compare Fig. 11, below Bretschneidera. Some features in the above de­ center, with Fig. 11, above center). Vessels solitary scriptions are widespread in wood of dicotyledons or in clusters, mean number of vessels per group = (e.g., scanty paratracheal axial parenchyma) and 1.96. Vessels rounded in transectional outline. thus are not likely to be synapomorphies for the Perforation plates mostly simple; occasional scalari­ two families. However, other features are not form perforation plates present, the bars sometimes common (perforation plates predominantly simple fused (Fig. 15). Lateral walls of vessels with pits but scalariform plates occasional in mature second­ alternate or opposite (Fig. 12), about 6 um in ary xylem) and are likely synapomorphies for at vertical diameter. Helical thickenings present on least the two families, and possibly some closely vessel walls (Figs. 13, 14). Thickenings slender, related families as well. The list of features in which occasionally anastomosing (Fig. 13, upper left) and Akania and Bretschneidera woods agree is surpris­ sometimes with shallow grooves between thicken­ ingly extensive. This list includes inconspicuous ings in close pairs (Fig. 14). Mean vessel diameter, growth rings, occasional perforation plates with 81 um. Mean number of vessels per mm2, 87. Mean bars numerous but often in aberrant arrangements, vessel element length, 624 um. Imperforate tra­ vessel to vessel lateral wall pitting predominantly cheary elements with simple pits and septate once alternate, vessel to axial parenchyma pitting scalari­ or twice (Fig. 16). Mean wall thickness of septate form, vessel to ray pitting scalariform to opposite, fibers, 6.0 um. Mean length of septate fibers, 1182 vessels relatively long, imperforate tracheary ele­ um. Axial parenchyma scant)' paratracheal (vasicen- ments all septate fibers with borders very vestigial tric) and terminal. Vessel to axial parenchyma or absent, axial parenchyma scanty paratracheal pitting scalariform. Vessel to ray pitting scalari­ (possibly with a few terminal cells in growth rings) form, transitional, or opposite (Figs. 17, 18). Rays in strands of 4-5 cells, multiseriate rays tall and multiseriate and uniseriate (Figs. 9,10,11), Hetero­ composed predominantly of procumbent cells, geneous Type IIA of Kribs (1935), tip cells and some wood nonstoried and with sparse dark deposits in sheathing cells of multiseriate rays upright, all cells cells. of uniseriate rays upright; ray cells otherwise Akania and Bretschneidera differ in minor wavs. procumbent (Fig. 10). Ray cell wall thickness varied Vessel to vessel pitting is alternate in Akania, but is (Fig. 18), mostly about 3.0 um. Borders present on sometimes alternate, sometimes opposite in 612 SYSTEMATIC BOTANY [Volume 21

'12. Wood sections of Bretsehneidera sinensis (SJRw-22016). 9. Transection; growth ring terminus about i the distance from the top of the photograph, where rays widen. 10. Tangential section; in addition to wide, tall multiseriate rays, several uniseriate rays are visible. 11. Transection to show nature of latewood: a layer of terminal axial parenchyma is present at the end of the growth ring, middle, just below the wide vessels. 12. Vessel-to-vessel pitting from radial section; opposite pitting is shown. Figs. 9,10, scale above Fig. 1; Fig. 11, scale above Fig. 4; Fig. 12, scale above Fig. 3. 1996] CARLQUIST: AKANIACEAE AND BRETSCHNEIDERACEAE 613

FIGS. 13-16. Wood details of Bretsckneidera sinensis. 13-14. Helical thickenings from vessels of radial sections (SJRw-22016). 15. Portion of a scalariform perforation plate from radial section (SJRw-21841). 16. Septate fibers from radial section (SJRw-22016). Figs. 13-15, bars = 10 pm; Fig. 16, scale above Fig. 3). 614 SYSTEMATIC BOTANY [Volume 21

FIGS. 17-18. Bretschneidera sinensis (SJRw-22016), pitting on ray cells from radial sections. 17. Scalariform to transitional pitting (horizontal axis of ray horizontal in photograph). 18. Scalariform and opposite pitting of ray cells, and, in sectional view at left, bordered pitting on tangential walls of ray cells (horizontal axis of ray oriented vertically). Figs. 17-18, scale above Fig. 3.

Bretschneidera. Bretschneidera has helical thickenings Bretschneidera are similar even in quantitative on vessel walls, whereas in Akania vessels there are features. grooves interconnecting pit apertures; these two Resemblances of Akania and Bretschneidera. features might be homologous; however, they can Conceding that woods of Akania and Bretschneidera, co-occur in some families of dicotyledons, such as respectively, are close to each other, does the wood Asteraceae (Carlquist 1966). The pits of Akania of this family pair resemble that of the other septate fibers are vestigially bordered, whereas I glucosinolate families? Because relevant mono­ was unable to find any borders on pits of septate graphs of some of these families are not at hand, fibers in Bretschneidera. Bretschneidera has uniseriate conclusions based on an adequate data base must rays, Akania lacks them. Crystals were observed in await further studies. Even so, analysis will not be rays of Akania but not in those of Bretschneidera. easy, because differences attributable to habit (e. g., When one compares these differences in character stem succulence of Caricaceae; herbaceousness of states (some of which are merely differences of Tropaeolaceae) mostly do not indicate phyletic degree) to resemblances between the two genera, relationship. one finds the similarities much more numerous, Do the wood patterns of Akania and Bretschneidera and many resemblances are features not wide­ support the idea, widely held by several leading spread in dicotyledons, so that the resemblances are phylogenists, that these two genera are sapindalean likely not all homoplasies. The differences between or at least not far from Sapindales? If one excludes the two genera are of a kind and degree one can Sabiaceae from Sapindales, a number of wood easily find within a family or even within a genus features common to Akania and Bretschneidera such as Meliosma (Carlquist et al. 1993). Akania and contrast with those of most but not all Sapindales. 1996] CARLQUIST: AKANIACEAE AND BRETSCHNEIDERACEAE 615

The wide, tall rays of Akania and Bretschneidera Rodman et al. (1993) and Conti et al. (1996) indicate, differ from the rays of most sapindalean families, Sapindales may lie close to the glucosinolate which have relatively narrow multiseriate rays. A families (Capparales in a new and expanded sense), scattering of Aceraceae and Anacardiaceae have Sabiaceae may deserve attention with respect to rays that are of medium width, but these do not features in addition to those from wood anatomv- approach the rays of Akania and Bretschneidera in width (Heimsch 1942; Metcalfe and Chalk 1950). Interestingly, occasional scalariform perforation LlTERATURE ClTED CARLQUIST, S. 1966. Wood anatomy of Compositae: a plates, reported here for both Akania and summary, with comments on factors controlling Bretschneidera, have been reported for 10 genera of wood evolution. Aliso 6: 25-44. Rutaceae, two genera of Anacardiaceae, and for the . 1971. Wood anatomy of Macaronesian and other latewood of Ailanthus of the Simaroubaceae (Met­ Brassicaceae. Aliso 7: 365-384. calfe and Chalk 1950). Fabaceae are now regarded . 1978. Wood anatomy and relationships of Bataceae, as a family of Sapindales (e.g., Thorne 1992). Such a Gyrostemonaceae, and Stylobasiaceae. Allertonia 5: large family might be expected to have such a wide 297-330. range of character state expressions that matches of —. 1985. Wood anatomy and familial placement of character states with those of Akania and Tovaria. Aliso 11: 69-76. Bretschneidera could be found, but these are more — and C. J. DONALD. 1996. Wood anatomy of likely homoplasies than synapomorphies with Tropaeolaceae in relation to habit and phytogeny. Akania and Bretschneidera (e.g., helical thickenings Sida 17: 333-342. in vessels). Such features of those two genera as —, P. L. MORRELL, and S. R. MANCHESTER. 1993. Wood septate fibers, imperforate tracheary elements with anatomy of Sabiaceae (s. I.); ecological and systematic implications. Aliso 13: 521-549. vestigial or simple pits and scanty vasicentric axial CHENG, J.-Q. 1980. Chinese tropical and subtropical timbers, parenchyma can be found widely in Sapindales, their distinction, properties, and application. Beijing: but without phyletic analysis, one must assume the Forestry Publishing House. possibility that these features are synapomorphies. CHENG, J.-Q., J.-J. YANG, and P. Liu. 1992. Anatomy and However, wood anatomy of Sabiaceae (Carlquist properties of Chinese luoods. Beijing: Forestry Publish­ et al. 1993) offers more numerous similarities than ing House. do other families placed in Sapindales. Sabiaceae CONTI, E., A. LlTT, and K. J. SYTSMA. 1996. Circumscription are often regarded as near Sapindales (e. g., Thorne of Myrtales and their relationships to other rosids: 1992), so they might be expected to retain some evidence from rbcL sequence data. American Journal features seen in Akania and Bretschneidera if this of Botany 83: 221-233. family pair and Sapindales had a common ancestry. CRONQUIST, A. 1981. An integrated system of classification of flowering plants. New York: Columbia Univ. Press. One can neglect Sabia in this comparison because DADSWELL, H. E. and S. J. RECORD. 1936. Identification of Sabia is a liana and thus wood of the arboreal woods with conspicuous rays. Tropical Woods 48: Meliostna is more pertinent for comparison. Notable 1-30. in Meliosma is occurrence of scalariform perforation DAHLGREN, R. M. T. 1980. A revised system of classification plates, characteristic of some species, whereas of the angiosperms. Botanical Journal of the Linnean others have only simple plates and some have both Society 80: 90-124. simple and scalariform perforation plates (Carl­ DEN OUTER, R. W. and W. L. H. VAN VEENENDAAL. 1981. quist et al. 1993). The multiseriate rays of Meliosma Wood and bar anatomy of Azima tetracantha Lam. are Heterogeneous Type 11A and often wide, as in (Salvadoraceae) with description of its included Akania and Bretschneidera, and in some species of phloem. Acta Botanica Neerlandica 30:199-207. ETLINGER, M. G. and A. KJAER. 1968. Sulfur compounds in Meliosma, as in Akania, uniseriate rays are lacking. plants. Recent Advances in Phytochemistry 1: 59-144. Hexagonal crystals, formed singly per cell, are GADEK, P. R., C. J. QUINN, J. E. RODMAN, K. G. KAROL, E. found in Meliosma, as they are in Akania. Features CONTI, R. A. PRICE, and E. S. FERNANDO. 1992. more commonly found in Sapindales, such as Affinities of the Australian endemic Akaniaceae: new septate fibers (with either vestigially bordered of evidence from rbcL sequences. Australian Systematic simple pits), scanty vasicentric axial parenchyma, Botany 5: 717-724. and presence of dark-staining compounds in rays GIBSON, A. C. 1979. Anatomy of Koeberlinia and Canotia and axial parenchyma, are also resemblances revisited. Madrono 26:1-52. between Meliosma and Akania and Bretschneidera GREGORY, M. 1994. Bibliography of systematic wood (Carlquist et al. 1993). If, as the cladograms of anatomy of dicotyledons. 1AWA Journal, Supplement 1:1-265. 616 SYSTEMATIC BOTANY [Volume 21

HEIMSCH, C. 1942. Comparative anatomy of the secondary producing plants. Part 2. Cladisrics. Systematic xylem in the Gruinales and Terebinthales of Wett- Botany 16:619-629. steins with reference to taxonomic grouping. Lilloa 8: , R. A. PRICE, K. G. KAROL, E. CONTI, K. J. SYTSMA, and 83-198. J. D. PALMER. 1993. Nucletoide sequences of the rbcL IAWA COMMITTEE ON NOMENCLATURE. 1964. Multilingual gene indicate the monophyly of mustard oil plants. glossary of terms used in describing wood anatomy. Annals of the Missouri Botanical Garden 80: 656-699. Winterthur: Verlagsanstalt Buchdruckerei Konkordia. , K. G. KAROL, R. A. PRICE, E. CONTI, and K. J. SYTSMA. ILIC, J. 1991. CSIRO atlas of hardwoods. Berlin: Springer- 1994. Nucleotide sequences of rbcL confirm the Verlag. capparalean affinity of the Australian endemic Gyros- KRIBS, D. A. 1935. Salient lines of structural specialization temonaceae. Australian Systematic Botany 7: 57 69. in the wood rays of dicotyledons. Bulletin of the TAKHTAJAN, A. 1987. Systema magnoliophytorum. Leningrad: Oficina Editoria "NAUKA." Torrey Botanical Club 64:177-186. TANG, Y. 1935. Notes on the systematic position of Lu, S. Y., K.-S. Hu, and F.-H. FAN. 1986. Bretschneidera- Bretschneidera sinensis as shown by its timber anatomy. ceae, a new family record for the flora of Taiwan. Bulletin of the Fan Memorial Institute of Biology 6: Quarterly Journal of Chinese Forestry 19: 114-119 (in 153-159. Chinese with English summary). THORNE, R. F. 1992. Classification and geography of the Luo, L. C. 1989. Economic timbers in Yunnan. Kunming: flowering plants. Botanical Review 58:225-348. Yunnan People's Publishing House. T/OBE, H. and C.-L. PENG. 1990. The embryology and METCALFE, C. R. and L. CHALK. 1950. Anatomy of the systematic relationships of Bretschneidera dicotyledons. Oxford: Clarendon Press. (Bretschneideraceae). Botanical Journal of the Lin- RODMAN, J. E. 1991a. A taxonomic analysis of glucosinolate- nean Society 103:139-152. producing plants. Part 1. Phenehcs. Systematic TOBE, H. and P. H. RAVEN. 1995. Embryology and Botany 16: 598-618. relationships of Akania (Akaniaceae). Botanical Jour­ . 1991b. A taxonomic analysis of glucosinolate- nal of the Linnean Society 118: 261-274.