OF ARTS AND SCIENCES. 205 



achenium is of thin and delicate texture, utricular, and it swells up into 

 a jelly-like mass in water: under the microscope some of its cells are 

 found to contain spiral threads. 



AiiTEMlsiA Linn. The technical distinctions between this genus 

 and Tanacetum are evanescent. As to the ribs of the akeue, these are 

 five and well marked in several species, among which are A. tridentata 

 and A. Norvegica. And A. Californica has not only these, but the 

 broad epigynous disk (more or less obvious in other species) is bordered 

 by an obsolete pappus. On the other hand, the ribs disappear in some 

 genuine Tanaceta, and the disk is very small in the turgid ripe achenia 

 of T. Sibiricum. The habit and inflorescence furnish the more obvi- 

 ous distinctions. 



Gray, 1. c. This I do not possess. It was described from a specimen in Dr. 

 Torrey's herbarium. 



■\- H- Achenia secus angulos hirsuta vel hirtella : folia breviora, crassiuscula. 



16. H. VERNALE Nutt. Glabellum vel tomentuloso- vel viscidulo-pubescens ; 

 foliis nunc integerrimis nunc rariter dentatis vel incisis ; pappi paleis obovatis 

 spathulatisve apice lacerato-denticulatis vel erosis corolla dimidio (rarius triple) 

 brevioribus. — Leptopoda pubenda Macbride in Ell. L. pinnatljida Nutt. — North 

 Carolina to Florida. 



17. H. BREviFOLiuM. Fere glabrum ; foliis brevibus plerisque spathulatis 



integerrimis ; pappi paleis obovatis subintegerrimis ; corollis disci apice atro- 



purpurascentibus. — Leptopoda brevifolia Nutt. in Trans. Amer. Phil. Soc. 7, 



p. 373 ; Torr. & Gray, 1. c. excl. var. — Georgia to Alabama. 



f 



§3. Hecubjea. (iTecuJcea DC.) Ligulas sjepius fceminese (vix fertiles?). Pap- 

 pus nullus vel minutissimus coroniformi-squamellatus. Caetera Leptopodce. 



18. H. SCORZOXER^FOLIUM Gray, Proc. Am. Acad. 7, p. 859. Ilecubcea scor- 

 zonerafoUa DC. Prodr. 6, p. 665, Deless, Ic. Sel. 4, t. 43. — Mexico, Alaman. 



Var. Ghiesbreghth Gray, 1. c. — Chiapas, Mexico, Ghiesbreght, no. 118, 

 527, new distribution. — See remarks at the head of this article. 



§4. OxTLEPis. (Oxylepis Benth. PI. Hartw.) Ligulae numerosae, lineari-cune- 

 at£e, fertiles. CoroUae disci tubo proprio sat longo instructae ! Pappi paleae 

 subulatae, enerviae, integerrimaa. Perennes, andinae, megacephalae, habitu 

 insigni. 



19. H. HooPESii Gray, in Proc. Acad. Nat. Sci. Philad. 1863, p. 65; Eaton 

 In S.Watson, Bot. King, p. 175. — Kocky Mountains in Colorado Territory 

 to the Sierra Nevada in California. 



20. H. LANATUM. Aclinea integrifolia HBK. Nov. Gen. & Spec. 4, p. 297, 

 t. 410. Oxijlepis Janata Benth. PI. Hartw. p. 87. Mexican Andes. — I have no 

 specimen of this, which Mr. Bentliam finds is a near relative of //. Iloopesii. 

 The receptacle must be much flatter, and the rays (about 40) much more numer- 

 ous, as shown in Kunth's figure : the tube of the disk-corolla is represented as 

 long as the limb. It is similar but shorter in the North American species. 



