During the past 150 years, casual nomenclatural practices have obscured what is generally agreed to be a natural systemof suprageneric classification in the Asclepiadaceae. An account of all subfamilial. tribal. and subtribal names published within the family is presented here with an evaluation of their nomenclatural status. Some problems of nomenclatural procedure peculiar to levels abovethe rank of genusand deriving from the natureof the "nomenclatural type" at these levels are discussed with particular regard to the present selection of available names.Members of the Asclepiadaceae have long attracted the attention of botanists by reason of the complicated structure of their flowers, We appreciate now that such morphological innovations as the gynostegiurn, translator apparatus, pollinium and staminal crown represent responses to insect pollination, and that they achieve a degree of specialization comparable to no other flowering plants except the orchids. Yet even before the validity of this interpretation was fully demonstrated by Robert Brown in 1831 in his paper on orchid and asclepiad fecundation-in fact, before the role of insects as the agents of cross-pollination in any of the flowering plants was either accepted or understood-variations in the highly modified androecium had been made the basis for the infrafamilial classification of the Asclepiadaceae.The basic scheme for the infrafamilial classification of the family was laid down by Robert Brown in 1810 when the separation of the Asclepiadaceae from the Apocynaceae was first proposed. Endlichers (1838) evaluation of the strengths and weaknesses of Brown' s classification has proven to be an accurate prediction of the focus which future taxonomic activity within the family would take. Endlicher believed that the suprageneric taxa, based on characters of the anthers and pollen. were natural but that the many genera, founded on minor variations in the form of the corolla and especially of the staminal crown, were artificial. Indeed, the value of staminal crown morphology in determining genera remains a matter of active debate. Estimates of the number of genera in the family (sensu lato . including the Periplocaceae) vary from at least 280 (Rendle, 1925) to as few as 75-100 (Lawrence, 1951). On the other hand, infrafamilial-suprageneric classification has never been a subject of much controversy. ) have accomplished worldwide taxonomic treatments of the Asclepiadaceae to at least the generic level. With few deviations, their infrafamilial-suprageneric classification schemes trace directly to Brown's (1810) original key to the genera of Asclepiadaceae. However, the names and ranks of the taxa in question have varied considerably, and numerous other authors, especially of local floras, have augmented this variation. The predictableIn style and format this study follows a previous one by S. P. Darwin (1976). The author wishes to thank Dr. Darwin for suggesting the projectand for many helpful discussions on the subject.

Summary A. T. Brongniart's investigations of the unique floral morphology of milkweeds (Asclepiadaceae) during the early 19th century were marked by incisive, original observation but also by misinterpretation.

Notes Dryopteris ludoviciana and D. x australis New to Arkansas.-Until recently, Arkansas was known to have three species and one hybrid of Dryopteris (Taylor & Demaree, Rhodora 81:503-548, 1979; Taylor, Arkansas ferns and fern allies, 1984), of which only D. marginalis (L.) Gray occurs frequently across the state. D. spinulosa (O. F. Muell.) Watt and D. x Jeedsii Wherry are each known from one locality, while D. celsa (Palmer) Small is known from three localities. Consequently, the discovery in 1984 of a species and a hybrid new to the state constituted significant additions to the fern flora of Arkansas and furnished important phytogeographic data on the distribution of Dryopteris taxa in eastern

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