SYNOPSIS OF CRATAEGUSSERIES APIIFOLIAE,CORDATAE, MICROCARPAE,AND BREVISPINAE(ROSACEAE SUBFAM.MALOIDEAE)1J. B. Phipps2ABSTRACT This paper revises four monotypic North American series of Crataegus (Rosaceae subfam. Maloideae). Of these,series Apiifoliae, Cordatae, and Microcarpae ail possess short-shoot and extension shoot leaves with secondary veins toboth the lobes and the sinuses, while series Brevispinae only exhibits this attribute on extension shoot leaves. Thebrilliantly red-fruited C. marshallii of series Apiifoliae is widespread and common in the southeastern United Statesand is most closely related to European species, particularly in foliage characters. The species-pair C. phaenopyrum(ser. Cordatae) and C. spathulata (ser. Microcarpae) have glossy foliage and small, orange-red, orbicular fruits, and area little less closely related to European species. Crataegus phaenopyrum is mid-Atlantic in range, westward to theOzarkian area, while C. spathulata is a common southeastern species. Crataegus brachyacantha (ser. Brevispinae) isthe most distinctive of the species treated, being black-fruited with different short-shoot foliage and restricted toLouisiana and the bordering parts of adjacent states. Line drawings and distribution maps are presented for eachspecies described, and representative specimens are cited. The selection of taxa for this paper also reflects the factthat the author had been intending to treat Crataegus for the now defunct Vascular Flora of the Southeastern UnitedStates (vol. 1, Cronquist, 1980). This paper is a further one of mine revising Cra-taegus (Rosaceae subfam. Maloideae) of NorthAmerica. The first (Phipps, 1988) was devoted toseries Aestivales (Sarg. ex C. K. Schneid.) Rehderand introduced the genus. This was followed by mymonograph of northern Mexican Crataegus (Phipps,1997) and an introduction to the red-fruited Cra-taegus of western North America (Phipps, 1998).The current paper assembles a group of monotypicseries ail with greater or lesser affinities to Euro-pean subgenus Crataegus. This subgenus was es-tablished by E1-Gazzar (1980) on the basis of itsdeeply lobed short-shoot leaves with veins to thesinuses. The taxa treated here comprise the nativeNorth American species with deeply lobed short-shoot leaves, as well as one in which the long-shootleaves alone are deeply lobed. El-Gazzar (1980) mistakenly held that ail Cra-taegus taxa with deeply lobed short-shoot leavespossessing veins to the sinuses were Eurasian.However, there are American series with this attri-bute, including series Apiifoliae (Loudon) Rehder,which fits very comfortably into subgenus Cratae-gus as perceived by El-Gazzar. Its foliage is of thetypical monogynoid shape, by which I imply ashape like that of C. monogyna Jacq., characteristicof many European species of section Crataegus.Further American series possessing lobed short-shoot leaves with veins to the sinuses are seriesCordatae (Beadle) Rehder and series Microcarpae(Loudon) Rehder, each of which has small flowers,small fruit (often orange-red in color), and 3-5 nut-lets. These last two series have no very close rel-atives outside North America. In addition to NorthAmerican Crataegus species with short-shootleaves lobed to their sinuses, there are also nativeAmerican taxa of Crataegus that include elementsintermediate between subgenus Crataegus and sub-genus Americanae El Gazzar-a reason that I amnot using El-Gazzar's subgeneric taxa in this revi-sion. The intermediate kinds are principally agroup of series normally lacking veins to the si-' The support of the National Sciences and Engineering Research Council of Canada under whose operating grantA-1726 this work was conducted, is gratefully acknowledged. Thanks are due to Susan Laurie-Bourque of Hull, Quebec,who drew the plates, and to the curators of numerous herbaria (A, AUA, BM, Cl, CLEMS, CM, COV, DHL, DOV,DUKE, FLAS, FSCL, FSU. GAM, GH, IBE, JSU, KY, LSU, LYN, MARY, MISSA, MO, MSC, NCSC. NCU, NLU, NO,NSU, SMU, SRH, TAEM, TAES, TENN, TEX, UARK, UNA, US, USCH, USF, USLH, VBD, VCU, VDB, WILLI, WVA)whose cooperation enabled the author to study such a wide range of material. 2 Department of Plant Sciences, The University of Western Ontario, London, Ontario, Canada, N6A 5B7. ANN. MISSOURI BOT. GARD. 85: 475-491. 1998.