28 LUNDELLIA DECEMBER, 2005

TAXONOMY OF SUBGENUS RYDBERGIA (: HELENIEAE: TETRANEURINAE)

Mark W. Bierner I School of Biological Sciences and Resources Center, The University of Texas, Austin, Texas 78712 I Present address: Boyce Thompson Arboretum, 37615 U.S. Highway 60, Superior, Arizona 85273 I Abstract: Hymenoxys subg. Rydbergia comprises H. brandegeei, H. grandiflora, and H. insignis. The treatment includes a discussion of the original circumscription of the taxa, the description of the genus Rydbergia to accommodate H. brandegeei and .l H. grandiflora, the eventual placement of Rydbergia within Hymenoxys as a subgenus, and relationships of the three taxa to one another and to other taxa of Hymenoxys. The treatment also includes synonymies, descriptions, and range maps for each of the species, and lectotypification of Actinella brandegeei.

Resumen: Hymenoxys subg. Rydbergia incluye H. brandegeei, H. grandiflora, y H. insignis. El tratamiento incluye una discusi6n de la circumscripci6n original de los taxones, la descripci6n del genero Rydbergia para acomodar H. brandegeei y H. grandiflora, la colocaci6n eventual de Rydbergia en Hymenoxys como un subgenero, y las relaciones filogeneticas de los tres taxones entre ellos y la de estos con los otros taxones de Hymenoxys. El tratamiento incluye tambien sinonimias, descripciones, mapas de distribuci6n para cada una de las especies, y lectotipificaci6n de Actinella brandegeei.

Keywords: Asteraceae, Helenieae, Tetraneurinae, Hymenoxys, Rydbergia

Hymenoxys Cass. subg. Rydbergia and A. insignis were thereby placed next to (Greene) Bierner comprises H. grandiftora A. chrysanthemoides ( = Hymenoxys (Torr. & A. Gray) K. L. Parker, originally chrysanthemoides) of subg. Phileozera (Bier-. described as Actinella grandiftora (Torrey ner, 2001) and species now separated from and Gray, 1845), H. brandegeei (Porter ex Hymenoxys into Greene (Bier­ A. Gray) K. L. Parker, originally described ner and Turner, 2003). at the varietal level as Actinella grandiftora Greene (1898) was clearly dissatisfied var. glabrata (Porter, 1874) and later at the with this arrangement. He placed most of specific level as Actinella brandegeei Porter the taxa of Gray's sect. Euactinella in Tetra­ ex A. Gray (Gray, 1878), and H. insignis (A. neuris, and most of the taxa of Gray's sect. Gray) Cockerell, originally described as Ac­ Hymenoxys in Picradenia Hook. Tetraneuris tinella insignis (Gray, 1883). Actinella Pers. is now recognized as a genus separate from was the generic name commonly used at Hymenoxys (Bierner and Turner, 2003 ), and that time (e.g., Torrey and Gray, 1842; Gray, 1883) for taxa now placed in Hyme­ Picradenia is now recognized as a subgenus noxys and Tetraneuris Greene. of Hymenoxys (Bierner, 2001). Greene When Gray (1883) described Actinella in­ (1898) then described Rydbergia to accom­ signis, he placed it along with A. brandegeei modate Actinella brandegeei and A. grandi­ and A. grandiftora in Actinella sect. Euacti­ ftora (Mexican species were not treated), a nella rather than in sect. Hymenoxys, based circumscription followed by Cockerell mainly on the morphology of the involucre. (1904), Rydberg (1906, 1915), Coulter and The phyllaries of taxa in sect. Euactinella are Nelson (1909), and Robinson (1981). Other in two or three subequal series; those of workers, such as Blake (1925), Parker taxa in sect. Hymenoxys are in two unequal (1950), Turner and Powell (1977), and Ka­ series. Actinella brandegeei, A. grandiftora, ris and Ryding (1994), felt there was no

LUNDELLIA 8:28--37. 2005 NUMBER 8 BIERNER: OF HYMENOXYS SUBG. RYDBERGIA 29

clear basis on morphological grounds for (although the pappus scales of H. insignis maintaining Rydbergia as a separate genus. are very small compared to those of the The submersion of Rydbergia in Hyme­ other two taxa). At the macro-morpholog­ noxys is supported by cytological and chem­ ical level, H. insignis looks something like a ical evidence. All three taxa have chromo­ taller, branched version of H. grandiflora some numbers of 2n = 30 (Turner et al., with heads about the size of those of H. 1961; Speese and Baldwin, 1963), which is brandegeei. The three taxa clearly form a the predominant chromosome number morphological trio similar to one another among the diverse taxa of Hymenoxys (e.g., and different from other taxa of Hyme­ Speese and Baldwin, 1952; Beaman and noxys. Turner, 1962; Strother 1966; Sanderson, The close relationship of Hymenoxys 1973; Turner et al., 1973). brandegeei, H. grandiflora, and H. insignis to Hymenoxys grandiflora produces a group one another is supported by chemical data of flavonoid compounds (notably flavone presented by Spring et al. (1994). Chemical aglycones that are methoxylated at the 6- similarity indices (the proportion of shared position of the A-ring but not at the 8-po­ to total compounds expressed as percent­ sition) that are identical to ones produced age) among the species pairs of H. brande­ by other species of Hymenoxys (Sanderson, geei-H. grandiflora, H. brandegeei-H. in­ 1975). In contrast, taxa that have been sep­ signis, and H. grandiflora-H. insignis were arated into Tetraneuris (Bierner and Turn­ 72%, 90%, and 63%, respectively. The high­ er, 2003) have a different flavonoid profile est similarity index of any subg. Rydbergia and produce flavone aglycones that are species to any other taxon of Hymenoxys methoxylated at both the 6- and 8-positions was 44% for H. grandiflora and H. bigelovii. of the A-ring (e.g., Bierner, 1978; Bierner In addition, the phenogram prepared by and Turner, 2003). Spring et al. (1994) from sesquiterpene lac­ Studies of sesquiterpene lactones and tone data placed these three species in the monoterpene glycosides of Hymenoxys and same clade with an infragroup average related genera by Spring et al. (1994) also chemical similarity index of 75%. The reli­ support the notion that Rydbergia is con­ ability of this analysis is supported by other generic with Hymenoxys. Hymenoxys bran­ groupings in the phenogram. For example, degeei, H. grandiflora, and H. insignis, like the species of subgenera Hymenoxys, Phileo­ the other taxa of Hymenoxys examined (ex­ zera, and Plummera were grouped into sep­ cept H. texana), were found to produce arate clades with infragroup average chem­ seco-pseudoguaianolides; these compounds ical similarity indices of 76%, 80%, and are not produced by taxa of Tetraneuris. 82%, respectively. The similarity index of Furthermore, like the other taxa of Hyme­ 90% for the H. brandegeei-H. insignis pair noxys examined (except H. texana), they did suggests that the connection of H. insignis not produce monoterpene glycosides; these of Mexico is probably to the more southern compounds are produced by all of the Te­ H. brandegeei. This contention is supported traneuris taxa examined. In 2001, Bierner by work documenting floristic similarities formally recognized Rydbergia as a subge­ between the northern Sierra Madre Oriental nus of Hymenoxys. of Mexico, where H. insignis is found, and Hymenoxys insignis is geographically dis­ the White Mountains of , the tant from the other two taxa (Fig. l); yet, southernmost edge of the distribution of H. the morphological similarities are striking. brandegeei (McDonald, 1993). All three have phyllaries in two or three su­ The relationship of Hymenoxys brande­ bequal series and leaves that are usually dis­ geei, H. grandiflora, and H. insignis to other sected to some extent. The disc and ray flo­ taxa of Hymenoxys is not at all clear. rets are very similar, differing mainly in size Morphologically, they are somewhat similar ;30 LUNDELLIA DECEMBER, 2005

l

A H. insignis

FIG. 1. Distribution of Hymenoxys brandegeei, H. grandiflora, and H. insignis. NUMBER 8 BIERNER: TAXONOMY OF HYMENOXYS SUBG. RYDBERGIA 31

to the taxa of subgenus Dugaldia, all having ted with impressed glands; basal leaf bases phyllaries in subequal series rather than in expanded, clasping, usually persistent. two unequal series (Bierner, 2001). The av­ HEADS 1-35 per plant, borne singly or.in erage chemical similarity index (Spring et paniculiform to corymbiform arrays. PE­ al,, 1994) of H. brandegeei, H. grandiflora, DUNCLES 1-10 cm, expanded apically, and H. insignis to H. hoopesii was relatively moderately to densely pubescent, often high at 32.7%, but their average chemical densely tomentose distally beneath the in­ similarity indices to the other two taxa of volucres, sparsely to moderately dotted with subg. Dugaldia, H. integrifolia and H. pine­ sessile glands. INVOLUCRES hemispheric to torum, were relatively low at 24% and subglobose, 10-25 X 15-30 mm. PHYLLA­ 23.3%, respectively. Hymenoxys brandegeei, RIES in 2 or 3 subequal series, herbaceous; H. grandiflora, and H. insignis had relatively outer phyllaries 10-24, free or basally con­ high average chemical similarity indices of nate 1/5 to 1/3 their lengths, green through­ 34% and 35% to H. odorata and H. out or yellow to yellow-green pro::rimally chrysanthernoides, respectively, of SlJbg. Phi­ and green distally, sometimes purple-red leozera, but they had similar average chem­ tinted on margins, lanceolate to narrowly ical similarity indices to H. cooperi, H, rus­ lanceolate, 7-15 X 1-4 mm, apict::s rounded byi, and H. subintegra of subg. Picradenia to acute to acuminate, abaxial faces sparsely (30.7%, 33.7%, and 36%, respectively). The to densely pubescent, sparsely to moderate­ highest average chemical similarity index of ly dotted with sessile and impressed glands, H. brandegeei, H. gran4iflora, and H. insig­ adaxial faces sparsely to 4ensely pubescent, nis to any other Hymenoxys taxon was 39% eglandular or sparsely to moderately dotted to H. bigelovii, the lone species of subg. with sessile glands; inner phyllaries 12-24+, Macdougalia. In fact, the similarity index free, usually yellow to yellow-green proxi­ between H. grandiflora and H. bigelovii was mally and green distally, sometimes green 44%, the highest of any subg. Rydbergia throughout, lanceolate to elliptic to obovate species to any other taxon of Hymenoxys. to oblanceolate, 5.2-12 X 0.8-3 mm, apices acute to acuminate, abaxial faces sparsely to TAXONOMIC TREATMENT densely pubescent, eglandular or sparsely to I-Jymeno:x:ys subg. Rydbergia (Greene) moderately dotted with sessile and im­ Bierner, Lundellia 4! 37-63. 2001, pressed glands, adaxial faces sparsely to Rydbergifl Greene, Pittonia 3: 270. 189.8. moderately pubescent, eglandl,llar or sparse­ TYPE SPECIES: Actinella grandiflora Torr. ly dotted with sessile glands. RAY FLORETS & A. Gray, Boston J. Nat. Hist. 5: 109, 14~4, pistillate, fertile; corollas yellow, 14- 1845. (= Hymenoxys grandiflora) 30 X 3.5-8 mm, lobes 3, abaxial faces gla­ brous or sparsely pubescent, sparsely to POLYCARPIC PERENNIALS. CAUDICES moderatdy dotted with sessile glands, ad­ unbranched or ± branched, AERIAL STEMS axial faces glabrous, eghindular. DISC FLO­ 1-10, erect, unbranched or branched dis­ RETS 150-400 +, bi:;ex:ual, fertile; corolla tally, green throughout to purple-red~tinted tubes yellow to yellow-brown, 14-Yi the to­ proximally or distally to purple-red-tinted tal length, limbs yellow, cylindric to cylin­ throughout, 8-80 cm, sparsely to densely dric-campanulate, 2.3~6X 0.6-1 mm, lobes pubescent, eglandular or sparsely dotted 5, glabrous or sparsely pubescept, eglandu­ with sessile glands. LEAVES basal and cau­ lar. RECEPTACLES hemispheric to globoid, line, alternate, blades simple and entire or palei;e none. CYPSELAE obpyra:rnidal to nar­ pinnately or bipinnately divided into 3~ rowly obpyra:rnidal, 2.3-3.7 X 0.7-1.1 mrn, 41 + segments, glabrous or sparsely to densely pubescent, hairs straight, forked, densely pubescent, sparsdy to densely dot- antrorse, eglcindular or sparsely dotted wit