IAWA Bulletin n.s., Vol. 11 (1), 1990: 47-56

WOOD AND BARK ANATOMY OF LAURACEAE m. ASPIDOSTEMON ROHWER & RICHTER

by

H. G. Richter Institut fUr Holzbiologie und Holzschutz, Bundesforschungsanstalt fUr Forst- und Holzwirtschaft, LeuschnerstraBe 91, 2050 Hamburg 80, F. R. O.

Summary A group of Madagascan species hitherto (1. Rohwer, Institute of Systematic Botany, ascribed to the genus Cryptocarya is segre­ University of Hamburg) these earlier findings gated on account of its widely differing mor­ were revived as a valid contribution to the phology and anatomy of wood and bark. The ever more complex taxonomy of the laurel new genus, Aspidostemon Rohwer & Richter, family. constitutes a small and very homogeneous Taxonomic background taxon, and its wood and bark characteristics The pantropical genus Cryptocarya R.Br. are described in detail. Aspidostemon con­ (approx. 250 species) presents itself as a trasts Cryptocarya proper in nearly all qualita­ rather homogeneous taxon despite its wide tive and quantitative features to a high degree. distribution in tropical and subtropical regions This does not only justify its segregation of the southern hemisphere. A small group of from, but also precludes any close relation­ Madagascan species, however, possess a ship with Cryptocarya. In order to properly ac­ wood structure incompatible with that of commodate Aspidostemon in the framework Cryptocarya (Richter 1981a). More recently of lauraceous taxonomy, additional evidence these species were reinvestigated morpho­ from other botanical disciplines is required. logically and found to be indeed very dif­ Key words: Lauraceae, Aspidostemon, Cryp- ferent from Cryptocarya (Rohwer & Richter tocarya, wood anatomy, bark anatomy, 1987). As there was not sufficient agreement taxonomy. with any other known lauraceous taxon, the species group was assigned the status of a Introduction new genus, Aspidostemon Rohwer & Rich­ This treatise on Aspidostemon is the third ter. Presently 11 species are recognised with­ in a series of papers dedicated to the system­ in Aspidostemon with A. perrieri designated atic wood and bark anatomy of Lauraceae. the type species: For the first time this series covers one of a 1. Aspidostemon perrieri (Danguy) Rohwer (= Cryp­ number of recently established new genera. tocarya perrieri Danguy) As with the two previous papers on Aniba 2. Aspidostemon dolichocarpum (Kosterm.) Roh- (Richter 1981b) and Licaria (Richter 1985) wer (= Cryptocarya dolichocarpa Kosterm.) the present publication meets the conditions 3. Aspidostemon caudatum Rohwer, spec. nov. of a) supply of adequate authenticated speci­ 4. Aspidostemon inconspicuum Rohwer,spec. nov. mens for examination and b) availability of a 5. Aspidostemon percoriacea (Kosterm.) Rohwer (= Cryprocarya percoriacea Kosterm.) recent systematic treatrnentiif 'the genus in 6. Aspidostemon glandulosum Rohwer, spec. nov. question (Rohwer & Richter 1987). The in­ 7. 'Aspidostemon trianthera (Kosterm.) Rohwer (= troduction of the new genus Aspidostemon is Cryptocarya lrianthera Kosterm.) rooted in an earlier study on wood and bark 8. Aspidostemon humbertianum (Kosterm.) Rohwer anatomy of Lauraceae (Richted98Ia) when (= Cryptocarya humbertiana Kosterm.) the respective species were considered 'ano­ 9. Aspidostemon synandra Rohwer, spec. nov. 10. Aspidostemon scintillans (Kosterrn.) Rohwer (= malous' within Cryptocarya and a possible Cryptocarya scintillans Kosterm.) segregation was implied. Through close co­ 11. Aspidostemon lacrimans (Kosterrn.) Rohwer (= operation with a young dedicated botanist Cryptocarya lacrimans Kosterm.)

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Undoubtedly, an additional species will forts of the Centre Technique Forestier Tro­ be forthcoming which comprises part of the pical (CTFT), Nogent-sur-Marne (France), material described and deposited in herbaria and its Madagascan affiliate, five bark speci­ as Cryptocarya louvelii Danguy. A formal mens were collected under the following ten­ transfer to Aspidostemon had to be postponed tative field identifications: because of a very mixed lot of vouchers 1. Cryptocarya perrieri (now Aspidostemon) under this name: The type specimen repre­ 2. Cryptocaryafulva sents a true Cryptocarya while a subsequent 3. Cryprocarya thouvenotii check of nine authenticated wood samples 4. Cryptocarya alseodaphnifolia showed four (SF 10950, 21829, 21830, 5. Cryptocarya louvelii (now in part Aspido­ 21831) to belong to Aspidostemon, and five stemon) (SF 10495, 10952, 10960, 10978, 10979) to Microscopic slides from all wood speci­ Cryptocarya. Consequently, a subsequent re­ mens were prepared as outlined in Richter vision of the material labeled Cryptocarya (1981a). Bark material was sectioned after louvelii is required. Coincidentally, this still penetration with polyethylene glycol (DP to be named Aspidostemon species repre­ 1500); further treatment followed the proce­ sents the well known commercial timber dures reported earlier in this series. 'Longotra mena', highly esteemed for its at­ The wood description adheres largely to tractive colour and grain, strength and natural the standards developed by the International durability. Associaten of Wood Anatomists in its most recent form (lAWA Committee 1989); bark Material and Methods description follows the terminology outlined The wood description of Aspidostemon is by Trockenbrodt (1989). based on 10 specimens of 7 species as well as 3 commercial wood samples attributed to Wood description 'Longotra' and labeled Cryptocarya louvelii (Figs. 1-3, Figs. 4-6 for comparison with Danguy (see Table 1). Cryptocarya) Bark specimens were still unavailable when General: Heartwood dark orange to red­ it was first suggested that the species group dish brown and well differentiated from the in question represented something entirely lighter coloured sapwood; vessels evenly dis­ different from Cryptocarya (Richter 1981a). tributed with hardly any gradient of pore size Meanwhile, through the much appreciated ef- and number along radial distance; growth in-

Table 1. Specimens examined of the genus Aspidostemon Rohwer & Richter.

RBHw No. Species Herbarium voucher 6929 Aspidostemon humbertianum SF 10967 = 696 R 182 (paratype) 1265 Aspidostemon lacrimans SF 12809 = 64 R 62 (holotype) 16014 Aspidostemon percoriaceum SF 10934 =Jerome 531 (paratype) 9742 Aspidostemon perrieri SF 10951 = 48 R 172 1181 Aspidostemon scintillans SF 10968 = 707 R 182 5969 Aspidostemon trianthera SF 12064 = 113 R 176 (holotype) s.n. Aspidostemon spec. (,Longotra mena') SF 10590 s.n. ibid. SF 21829 s.n. ibid. SF 21830 s.n. ibid. SF 21831 2342 ibid. Commercial specimen 5371 ibid. ibid. 9781 ibid. ibid.

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Figs. 1-3. Secondary xylem of Aspidostemon in transverse, tangential and radial view. -la, 2a & 3: A. percoriacea. -lb & 2b: Aspidostemon spec. = 'Longotra mena'. Note storeyed rays in Fig. 2a & b. - Figs. 4-6. Secondary xylem of Cryptocarya (Madagascar) in transverse, tan­ gential and radial view. - 4: C. helicina. - 5 & 6a: C.fulva. - 6b: C. spathulata. Note marginal parenchyma bands (Fig.4, arrows) and horizontal stratification of fibres (Fig. 6b, arrows) under polarised light. Scale bar = 200 IJ.m.

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Downloaded from Brill.com09/23/2021 08:51:28PM via free access Richter - Wood and bark anatomy of Aspidostemon 51 crements mostly indistinct; grain typically 3-4 (up to 5) cells wide; heterogeneous, interlocked giving rise to an attractive ribbon body cells procumbent with 1 marginal row figure on radial surfaces; ripple marks pres­ of upright and/or square cells; height of ent, ± distinct to the naked eye, approx. 2.5 tallest rays 0.3-0.5 mm; generally 7-8, in to 3 tiers/mm; texture medium, surface non­ some specimens up to 13 rays/mm; vessel­ fluorescent; without specific odour or taste; ray pits similar to intervascular pits in cross­ wood dense and heavy, specific gravity '" fields pertaining to procumbent cells, typi­ 0.80-0.90 g/cm3 (6-8% mc). cally enlarged with much reduced borders Anatomy: Wood diffuse porous (Fig. 1); (scalariform, diagonal and palisade pattern) vessels predominantly in short radial multi­ in square/upright cell crossfields; usually ples of 2-3, interspersed with solitary ves­ replete with reddish-brown gum deposits in sels and few clusters; thin-walled, mostly heartwood. oval on outline; 20-32/mm2 in mature stem Secretory (oil) cells common in the sec­ wood, up to 45/mm2 in specimens from ondary xylem, most frequently associated young trees (or branches?); average tangen­ with rays (marginal rows), to a lesser degree tial diameter 80-140 J.UD, that of largest ves­ with the rare axial parenchyma and inter­ sels 140-170 (up to 200) Ilm in mature spersed between fibres; often of considerable wood, from 90-150 Ilm in younger samples; size (up to 100 J.UD in diameter and 400 J.UD in perforation plates predominantly simple, oc­ length) and easily mistaken for smaller ves­ casionally scalariform (Fig. 8) with less than sels. 10 bars; intervascular pitting alternate, pits Crystalline and silica deposits not observ­ circular to polygonal depending on varying ed in the specimens examined. degrees of crowding, 6-8 Ilm in diameter (vertical dimension); some ornamentation Bark description present in pit cavities (vestures or incrusta­ (Figs. 9, 11, 12, Figs. 10, 13, 14 for com­ tions ?); helical vessel wall thickenings oc­ parison with Cryptocarya) casionally present; thin-walled tyloses com­ mon, gum deposits not observed. General, as taken from literature (Koster­ Fibres in irregular arrangement, polygonal mans 1957, NN 1954) and own observa­ in cross section, thin- to thick-walled; with tions: Bark reddish brown, smooth, outer simple to minutely bordered pits; regularly layers peeling off in circular flakes of 5-10 septate (1-3 septa per fibre); in heartwood cm in diameter; inner bark loosely attached to replete with reddish brown gum deposits the xylem and rather brittle, 10-15 mm thick; (Fig. 7); growth increment boundaries some­ slash granular, reddish brown; dry bark slight- 1y aromatic. times weakly marked by 2-3 rows of thicker walled, radially flattened fibres. Anatomy: Secondary phloem composed of Parenchyma inconspicuous, scanty para­ conducting tissue (sieve tubes and companion tracheal in uniseriate and mostly incomplete cells) and thin-walled phloem parenchyma sheaths around vessels. cells in, respectively, decreasing and increas­ Rays distinctly to irregularly storeyed ing proportions with distance from the cam­ (Fig. 2a, b); (1-) 2-3, in some specimens bium; with scattered, small to medium-sized

Fig. 7. Aspidostemon percoriacea (radial): septate fibres and dark organic compounds in fibre lumina. - Fig. 8. A. lacrimans (radial): scalariform perforation plate. - Fig. 9. Secondary phloem of Aspidostemon from cambium (bottom) to last-formed periderm (top). Note scattered sclereid bundles and large idioblasts (oil cells) throughout. - Fig. 10. Secondary phloem of Cryptocarya from cambium (bottom) to last-formed periderm (top). Note scattered scelereid bundles in proximity of cambium; sclereids formed in ray dilatation tissue occupy most of the outer phloem. Scale bar = 200 Ilm.

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Figs. 11 &12. Close-up of sclereid bundles of Aspidostemon bark in transverse (11) and radial (12) view. Note finite axial extension of bundles and elongated ('columnar') individual sclereids. - Figs. 13 & 14. Close-up of sclereid bundles of Cryptocarya bark in transverse (13) and radial (14) view. Note more or less isodiametric individual sclereids and large number of prismatic crystals. Scale bar = 200 J.l111.

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Table 2. Differences in secondary xylem and phloem features between AspidtJstemon and Cryptocarya from Madagascar.

Feature Aspidostemon Cryptocarya Wood Vessels / pores average tangential diam. 80-140 IJ.m 140-200 IJ.m average N/mm 17-32 (45) 4-11 vertical diameter inter- vessel pits 6-8 1J.m 9-111J.ffi vessel perforations simple + scalarifonn (rare) exclusively simple helical thickenings present (occasionally) absent Fibres morphology septate non-septate pits simple to minutely bordered distinctly bordered contents (heartwood) gum deposits none arrangement irregular horizontally stratified Axial parenchyma scanty paratracheal only a) scanty paratracheal to vasicentric b) zonate marginal bands Wood rays arrangement storeyed non-storeyed composition 1 row of upright/square cells 1-4 rows of upright/square cells contents (inorganic) not observed small prismatic crystals Secretory cells oil cells only oil and/or mucilage cells Bark Mechanical tissue phloem fibres absent absent sclereids axially elongated ± isodiametric contents (inorganic) absent prismatic crystals Parenchyma lignified parenchyma* absent present Phloem rays arrangement '" storeyed non-storeyed

* The term 'lignified parenchyma' is preferred to the descriptor 'sc1erified longitudinal parenchy­ chyma' used by Bamber and Summerville (1979) to characterise phloem parenchyma cells which develop a secondary lignified wall (birefringent under polarised light) but lack the mor­ phological characteristics of sc1ereids (polylamellate, pit canals). Lignified parenchyma occurs in a number of lauraceous genera (Richter 1981 a) but is most prolninent in Cryptocarya. It usually sets out with sieve tube collapse (few cell rows outside the cambium) and thereafter constitutes the main tissue of the secondary phloem. It is easily distinguished from sclerified cells by differential staining (sclereids: yellow; lignified parenchyma: red) with chrysoidine/ acridin red, and from normal parenchyma and sieve tubes by viewing in polarised light (lignified parenchyma: birefringent).

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sclereid bundles (Fig. 9) consisting of axially The most diagnostic features separating elongate cells with polylamellate walls ('col­ Aspidostemon from Cryptocarya are to be umnar sclereids' fide Chattaway 1959). Scle­ seen in the parenchyma distribution (Figs. 1 reid bundles constitute the only mechanical & 4) and in the arrangement of wood and tissue of the secondary phloem and are al­ bark rays: In Lauraceae zonate marginal bands ways of finite longitudinal extension (0.5 to are characteristic of and largely restricted to 5 mm in length) and extremely variable in the BeilschmiedialCryptocarya complex that diameter from 100 (2 to 3 cells) to 500 J.Lm includes, beside the main genera, Endiandra, (more than 30 cells); other sclereid types and Potameial Syndic/is, Triadodaphne, and Ra­ phloem fibres not observed. vensara, respectively; the storeyed structure The secondary phloem phases gradually is a specialised condition extremely rare in into few layers of cortical parenchyma inter­ Lauraceae, observed in few individual spe­ spersed with some isolated isodiametric scle­ cies (i.e. Beilschmiedia kweo) or specimens reids or small sclereid groups, possibly con­ (of Mezilaurus and Potameia). Moreover, stituents of a sclereid ring formed earlier in ripple marks in these taxa are of the echelon the young bark and driven apart by dilata­ type (irregular) while most Aspidostemon tion. The cortex is followed by the first of specimens show a very regular ray stratifica­ two or more sequential periderms consisting tion (Fig. 2a, b). of up to 10 rows of rectangular, radially The array of relevant diagnostic wood fea­ oriented cells. The tissue between periderms tures of Aspidostemon is complemented by resembles the cortex in all aspects. septate fibres (Fig. 7) and, to a lesser degree, Phloem rays similar to wood rays in over­ diameter of intervascular pits. Quantitative all dimensions and arrangement (storeyed), vessel characters (diameter, number/mm2) without significant alterations throughout and ray composition, although quite different most of their radial course. Dilatation takes from Cryptocarya, need not be employed for place only in the outermost secondary phloem, safe differentiation. mainly by tangential cell division. When tra­ Gross structure of the secondary phloem versing sclereid bundles ray tissue becomes of Aspidostemon and Cryptocarya appears equally sclerified. similar at first sight: both taxa lack phloem Secretory (oil) cells frequent and large fibres and possess sclereid bundles of similar (up to 120 J.Lm in diameter) in the secondary size and distribution (Figs. 9,10). Yet scle­ phloem and, to a lesser degree, the cortex, reid morphology and inorganic contents as giving Aspidostemon bark a spongy appear­ well as ray arrangement reveal fundamental ance. differences: Sclereid bundle constituents are Small acicular crystals present in ray and ± isodiametric and contain large prismatic axial parenchyma cells. crystals in Cryptocarya vs. axially elongated ('columnar') without inorganic contents in Aspidostemon (Figs. 11-14). This latter con­ Discussion dition is shared by Aspidostemon with a Aspidostemon, as based on the wood and rather diverse assembly of lauraceous taxa bark specimens investigated, represents a such as the neotropical Aniba, Licaria, and remarkably homogeneous and clearly defined part of Ocotea, the Asiatic Neocinnamomum, structural group. At the same time, it is fun­ and the recently described Dahlgrenodendron damentally different from Madagascan Cryp­ from South Africa (Van der Merwe & Van tocarya in qualitative as well as quantitative Wyk 1987). Outside Cryptocarya isodia­ characters as shown in Table 2. metric sclereids in conjunction with large The overall structural pattern of Crypto­ prismatic crystals can be found in the majori­ carya is somewhat more differentiated than ty of Beilschmiedia species (few contain that of the very homogeneous Madagascar dense silica instead) and Endiandra (Raven­ segment. However, none of the slightly di­ sara and Potameia will probably have to be vergent structural groups bears any resem­ added here, but no bark specimens are as yet blance with Aspidostemon. available for examination). Mezilaurus also

Downloaded from Brill.com09/23/2021 08:51:28PM via free access Richter - Wood and bark anatomy of Aspidostemon 55 features the same sclereid configuration but Now that much more knowledge, in­ no crystals. Exceptionally, a small group of cluding wood and bark structure, has become Cryptocarya species from southeastern Brazil available the weighting of characters in laura­ has scelereid bundles composed of columnar ceous taxonomy has reached a new dimen­ sclereids replete with dense silica. sion. This renders superfluous Kostermans' The feature 'lignified parenchyma' (see (1988) remark that splitting up existing Table 2) present in Cryptocarya and absent in taxonomic units "serves as a nice plaything Aspidostemon, is a useful secondary charac­ for some taxonomists" (with reference to ter for generic differentiation when dealing Rohwer & Richter 1987). Neither splitting with the taxa discussed here. nor unifying are per se detestable acts of taxonomic self-indulgence as long as the The exomorphic characters (leaves, flow­ underlying arguments are well founded. With ers, fruit) of Aspidostemon and Cryptocarya Aspidostemon this is definitely the case. In are described in detail by Rohwer & Richter fact, this new genus contrasts Cryptocarya (1987). As shown there, the diagnostic dif­ s.l. to such a degree that it does not seem ferences are largely restricted to the floral related at all; Beilschmiedia and affiliated structure and are certainly less obvious than genera appear equally distant. Moreover, the those related to wood and bark structure. combined evidence from exomorphic as well Moreover, the two genera agree completely as wood and bark characters does not suggest in their fruit structure, a unifying trait that, in an immediate affinity to any of the laura­ absence of flowers, might easily lead to ceous taxa presently known. More data from mislabeling Aspidostemon for Cryptocarya disciplines other than morphology and anat­ as exemplified by the vouchered wood spe­ omy need to be considered before Aspido­ cimens of Cryptocarya louvelii examined stemon can be assigned its proper place in the here (see Taxonomic background) and also Lauraceae. bark specimens: the material attributed to C. perrieri (= Aspidostemon) turned out a true Cryptocarya while that of C. julva (= true References Cryptocarya) is actually Aspidostemon. Bamber, R.K. & R. Summerville. 1979. In his original treatment of Cryptocarya Taxonomic significance of sclerified tissue from Madagascar Kostermans (1957) had in the barks of Lauraceae. lAWA Bull. already recognised some of the morpholo­ 79/4: 69-74. gical differences which eventually lead to Chattaway, M.M. 1959. The anatomy of the segregation of Aspidostemon: "Le genre bark. VII. Species of Eugenia (sens. lat.). Cryptocarya R. Br. est represente a Madagas­ Trop. Woods 111: 1-14. car par deux groupes, don't l'un se distingue IAWA Committee. 1989. IAWA List of par les feuilles opposees, generalement par microscopic features for hardwood identi­ les etarnines internes steriles, et par les 6 eta­ fication. IAWA Bull. n.s. 10: 219-332. mines externes reduites a 3 etamines fertiles. Kostermans, A.J.G.H. 1957. Le genre Ce groupe se distingue aussi par les carac­ Cryptocarya R.Br. (Lauracees) a Mada­ teres suivants, indiques surl'echantillon S.F. gascar. Bull. Jard. Bot. Bruxelles 27: 8689: Toutes les especies de Cryptocarya 173-188. a feuilles opposees ont une ecorce epaisse, Kostermans, A.J.G.H. 1988. Materials for rosee sur tranche, assez molle, a rhytidome a revision of Lauraceae V. Reinwardtia caduc par plaques (platanoide). Le bois a une 10: 439-470. structure etagee tres neUe que se voit bien Merwe, J.J.M. van der & A.E. van Wyk. quand on fait une flache Ie tronc." However, 1988. Dahlgrenodendron, a remarkable while sensitive to these differences, fruit struc­ genus from Natal and Pondoland. South­ ture apparently received priority by Koster­ afro Tydskr. Plantk. 54: 80-88. mans, and the species in question were N.N.1954. Longotra: Fiche botanique fores­ assigned only subgeneric (sectional?) status tiere, industrielle et commerciale. Bois et within Cryptocarya/Madagascar. Forets des Tropiques No. 33: 37-40.

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Richter, H.O. 1981a. Anatomie des sekun­ Rohwer, 1.0. & H.O. Richter 1987. Aspi­ diiren Xylems und der Rinde der Laura­ dostemon, a new lauraceous genus from ceae. Sonderb. Naturwiss. Vereins Ham­ Madagascar. Bot. lahrb. Syst. 109 (1): burg 5: 1-148. 71-79. Richter, H.O. 1981b. Wood and bark anat­ Trockenbrodt, M. 1989: Entwicklung, Varia­ omy of Lauraceae I. Aniba Aublet. IAWA bilitlit und taxonomische Bedeutung der Bull. n.s. 2: 79-87. Rindenstrukturen von Quercus robur L., Richter, H.O. 1985. Wood and bark anat­ Ulmus glabra Mill., Populus tremula L. omy of Lauraceae II. Licaria Aublet. und Betula pendula Roth. PhD Thesis, IAWA Bull. n.s. 6: 187-199. Univ. Hamburg (unpublished): 216 pp.

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