STUDIES IN THE EUPATORIEAE (ASTERACEAE) . XXXVIII. A NEW GENUS, PETERAVENIA . R. M. King and H. Robinson Smithsonian Institution, Washington, D.C. 20560. Five Eupatorian species from Mexico and Central America represent a distinctive previously unnamed genus having decid-uous pappus setae, discolored phyllaries, and cordate leaves. The pappus setae alone are sufficient to distinguish the genus, being very narrow at the base and noncontiguous but enlarged at the tip. The genus is Critonioid in its smooth corolla lobes and its usuai^ simple style base. One feature that is more reminiscent of Ageratina , however, is the usually high placement of the embryo in the achene. We take great pleasure in naming this new genus in honor of our good friend and colleague, Dr. Peter H. Raven of Stanford University. Although the Asteraceae is not his main speciality, his contributions to our knowledge of the family are very significant . Peteravenia R.M.King & H.Robinson, genus nov\im Asteracearum. Plantae grossae herbaceae vel frutescentes erectae usque ad 4 m. altae, pauce ramosae. Folia opposita longe petiolata, laminis corHatis plerumque serratis. Inflorescentiae laxe paniculatae. Involucri squamae ca. 25 plerumque oblongae inaequilongae 3-4-seriatae; receptacula valde convexa glabra. Flores 18-35 in capitulo; corollae anguste infimdibiilares 5-lobatae, extus glabrae, celliilis oblongis vel linearibus, parietibus plerumque sinuosis, lobis aequilateraliter triangu-laribus vel longioribus ad apicem induratis minute scabris, stomatibus nullis; filamenta antherarum in parte superiore angustata, cellulis rectangularibus vel infeme quadratis, parietibus anntilate vel intricate omatis, cellulis exothecial-ibus pleiTimque subquadratis, appendicibus antherarum late triangularibus obtusis vel truncatis; styli infeme glabri non vel leniter nodulosi, appendicibus linearibus vel anguste clavatis minute papillosis vel sublaevibus. Achaenia prismatica 4-5-costata setifera, infeme plerumque angustiora; carpopodia aliquantiom distincta, cellulis quadratis parietibus tenuibus; pappus setiformis uniseriatus, setis ca. 30 scabris facile deciduis, infeme angustis non vel vrx contiguis, supeme anguste clavatis, cellulis apicibus acutis. Embryones supeme dispositi. 39k
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