IAWABulletinn.s., Vol. 1 (3), 1980 121 WOOD ANATOMY OF HORSFIELDIA (MYRlSTICACEAE) by J. E. Armstrong and T. K. Wilson Department of Biological Sciences, Illinois State University, Normal, Illinois 61761, U. S. A. and Department of Botany, Miami University, Oxford, Ohio 45056, U.S.A. Summary The wood of Horsfieldia is, on the whole, (Garratt, 1933) was based on a small number very homogeneous. The greatest differences of specimens and the descriptions were rather observed are related to the relative age of the general. Siddiqi and Wilson (1974) have provi­ specimens. In contrast to the wood of Knema ded a comprehensive study of the genus the mature wood of Horsfieldia lacks oil cells Knema. Siddiqi and Wilson were unable to in the rays and has a predominance of simple weigh intra-family relationships due to the lack perforation plates as well as shorter, wider of information on the other genera. From vessel elements and wider rays. The homogenei­ available information they judged Knema to be ty of the secondary xylem of Horsfieldia makes more similar to Myristica than Gymnacranthera it of little taxonomic value on a specific level. and supported Garratt's conclusion that Based on wood anatomy, Horsfieldia can be Horsfieldia stands apart from the other three distinguished from the other three Asiatic southeast Asia genera. Hopefully this study will genera of the Myristicaceae. help clarify the position and relationships of Horsfieldia within the Myristicaceae, as well as Introduction determine whether there is any anatomical Horsfieldia is the second largest genus of support for the division of the genus into the nutmeg family with 70-80 species. War­ sections. burg (1897) recognized 52 species of Horsfiel­ dia which he placed into 3 sections based upon Methods and Materials characteristics of the staminate flowers. In his Fifty specimens representing 31 species of revision of the Malayan Myristicaceae, Sinclair Horsfieldia were examined. Collections are (1958) felt that these sections were largely cited according to the recommendations by artificial and declined to place the Malayan Stern and Chambers (1960). This sample species into sections. However, Sinclair did use included 23 of Warburg's (1897) original 52 the perianth structure to tentatively divide the species and represented all three sections of genus into two sections depending upon the genus (Table 1). Sections Pyrrhosa and whether the perianth was bivalved or trivalved. Irya are each subdivided on the basis of perianth The only survey of myristicaceous wood lobing, bivalved or trivalved. Table 1. Sections of the genus Horsfieldia after Warburg (1897) Species examined Section Pyrrhosa Subsection Bivalves: H. ardisiifolia, H. novae-lauenburgiae, H. polyantha. H. subtilis. H. tuberculata Subsection Eupyrrhosa: H. amygdalina. H. glabra. H. macrocoma. H. motleyi. H. superba. H. tomentosa Section Irya Subsection Euirya: H. irya. H. crassifolia. H. sucosa Subsection Trivalves: H. brachiata. H. lemanniana. H. subglobosa Section Orthanthera: H. iryaghedhi. H. sylvestris 122 IAWA Bulletin n.s., Vo!. 1(3),1980 The wood blocks were prepared and section­ nes: T, Bartlett (USw-298 I 6); M(CLPw-9890). ed using standard techniques. The sections H. motleyi Warb., Borneo: M(MADw-4272). H. were stained with modified Heidenhain's novae-Iauenburgiae Warb., New Guinea: M(SJR­ hematoxylin (Wilson & Shutts, 1957) and w-29462). H. obscurinervia Merr., Camarines: iron-alum safranin (Gray & Pickle, 1956). M(CLPw-26503). H. pilifera Markgr., New Small samples were macerated with Jeffrey's Guinea: M(WIBw-3234). H. polyantha Warb., fluid (Johansen, 1940). The macerated wood New Guinea: M(WIBw-9064). H. polyspherula was stained with iron-alum safranin and dehy­ (Hook. f.) Sinc!., Indonesia: T(USw-29412); drated with an acetone series to prevent Borneo: M(USw-30853). H. subglobosa (Miq.) excessive destaining. While mounting the tissue Warb., Indonesia: T, Bartlett (USw-29280, a binocular dissection microscope was used to USw-29329); T(USw-29377); Borneo: M(USw- help isolate large numbers of vessel elements 23571). H. subtilis Warburg, New Guinea: from the numerous surrounding fibres. The M(WIBw-10153). H. sucosa (King) Warb., isolated vessel elements were mounted on a Malaya: M(SJRw-23606). H. superba Warb., single slide. The additional preparation time Malaya: M(SJRw-39096). H. sylvestris Warb., was more than adequately compensated for Singapore: T, Canright 1017 (MU); Indonesia: when 25-75 vessel elements could be easily ob­ M(BZFw-29884); New Guinea: M(WIBw- served without a lengthy search of numerous 1151). H. tomentosa Warburg, Indonesia: T, slides. This is especially useful in a wood Rahmat si Boeea (USw-27588, USW-28040). with relatively few vessel elements. H. tuberculata (Schum.) Warb., Melanesia: The measurement data for each anatomi­ M(SJRw-22968). H. cf xanthina Airy Shaw, cal parameter were accumulated from a ran­ Borneo: M, Pickles (USw-16984, USw-16987). domly selected sample of 30 per specimen. The angle of the end wall of vessel elements was Results measured from the vertical with a transverse There is a great deal of similarity among end wall having an angle of 90°. Descriptive the various specimens of Horsfieldia that terminology follows the recommendations of were examined. The greatest differences were the Committee of Nomenclature, International directly related to the relative ages of the Association of Wood Anatomists (1964). Size wood specimens. The wood specimens obtain­ classifications conform to the recommenda­ ed from various sources represent either young tions of Chattaway (1932) and the Committee stems or twigs, which are easily identified, on the Standardization of Terms of Cell Size, or blocks of wood, which because of their International Association of Wood Anato­ parallel, non-converging rays must have come mists (1937,1939). from peripheral portions of larger stems or branches. While the maturity of the latter Specimens examined (T-twig, M-mature): H. specimens is stilI open to question, the obvi­ acuminata Merr., Philippines: M(CLPw-29 I 76); ous homogeneity of these wood specimens is M(CLPw-29146). H. amygdalina Warb., Indo­ sufficient rational for presenting the obser­ nesia: M, Krukoff 4138 (USw-636 I). H. ar­ vations for twig specimens and the mature spe­ disiifolia Warb., New Guinea: M(CLPw-28297); cimens separately. In addition, anatomists are M(WIBw-1003). H. bivalvis (Hook. f.) Merr., often confronted with the task of attempting Indonesia: T, Rahmat si Boeea (USw-28420). an identification or comparison with little H. brachiata Warb., Indonesia: T, Rahmat si more than a twig from an herbarium specimen. Boeea (USw-28587); Borneo: M(USw-30850). Descriptions of mature wood are of little use in H. carnosa Warb., Borneo: M(USw-30852). H. comparisons with such specimens. The age confertiflora Merr., Philippines: M (CLPw- determination of the specimens is indicated in 22551); M(SJRw-22111). H. crassifolia Warb., the list of specimens examined. Borneo: M(USw-30851). H. glabra (Blume) Warb., Indonesia: M(SJRw-21681); T, Rahmat Wood from Twig Specimens si Boeea (USw-2801 0, USw-29020, USw-29058, There were 15 specimens of Horsfieldia USw-29 108). H. helwigii Warb., New Guinea: wood from young twigs examined. These M(WIBw-2733); M(USw-24076). H. irya specimens represent the first 1-1.5 cm of Warb., New Guinea: M(WIBw-873). H. irya­ secondary xylem formed. ghedhi (Gaertn.) Warb., Ceylon: M, For. Res. Vessels - The vessels are usually very numer­ Inst. 194C (USw-2l761). H. lemanniana Warb., ous, and diffusely distributed in pairs (58%), Malaya: M(SJRw-23603). H. macro coma solitarily (31%), or in short radial chains (11%) Warb., New Guinea: M(WIBw-11182); M(USw- (Table 2, Fig. I). Vessel element size is modera­ 23956). H. megacarpa Merr., Philippines: T, tely small to medium in diameter, and medium Barbon 695 (MU). H. merrillii Warb., Philippi- to moderately long, with a length to width .