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September 1999] KRON ET AL.—PHYLOGENETICS OF ANDROMEDEAE 1297 Fig. 3. Strict consensus of 42 trees found in the parsimony analysis of rbcL data. L 503, CI 0.58, RI 0.50. Decay values are below lines, and parsimony jackknife values are above lines. Taxa traditionally placed in the tribe Andromedeae are in boldface. Fig. 4. Strict consensus of four trees found in the parsimony analysis of matK data. L 980, CI 0.65, RI 0.62. Decay values are below lines, and parsimony jacknife values are above lines. Taxa traditionally placed in the tribe Andromedeae are in boldface. Fig. 5. Strict consensus of four most parsimonious trees obtained from the combined analysis of rbcL and matK data. L 1495, CI 0.62, RI 0.58. Decay values are below lines, and parsimony jacknife values are above lines. Taxa traditionally placed in the tribe Andromedeae in boldface. pendently in Diplycosia and Gaultheria. Tepuia and Diplycosia form a moderately well-supported clade (d3, 71% bootstrap) supported by apical connate bracteoles (#25) and anther tubules (no. 41), as do Gaultheria and Pernettya (d4, 84% bootstrap), which may be supported by fleshy, colorful sepals. Gaultheria likely is paraphyletic, justifying the inclusion of Pernettya. The monophyly of Leucothoë is not at all supported. DISCUSSION Results of phylogenetic analyses based on morphology, rbcL, and matK sequences (Figs. 1–4) are generally similar, although analyses based on single character sets are less well resolved than the combined analyses (Figs. 5–6). We note that the cladogram resulting from the analysis based on all three data sets, i.e., morphology and rbcL and matK sequences (Fig. 6), is better resolved and shows stronger statistical support for the various internal clades than any other tree produced in our analyses. This tree strongly supports the monophyly of the Lyonia group (including Lyonia, Craibiodendron, Agarista, and Pieris) and the Vaccinieae (including numerous inferior-ovaried genera), but provides only weak support for the Gaultheria group (circumscribed so as to include Andromeda and Chamaedaphne, as well as Zenobia, Leucothoë, Diplycosia, Tepuia, Gaultheria, and Pernettya). Recognition of
1298 AMERICAN JOURNAL OF BOTANY [Vol. 86 Fig. 6. Single most parsimonious tree obtained from the combined analysis of morphology, rbcL, and matK data. L 1565, CI 0.61, RI 0.59. Decay values are below lines, and bootstrap values are above lines. Taxa traditionally placed in the tribe Andromedeae are in boldface. the Andromedeae, as traditionally circumscribed (see Stevens, 1969, 1971, 1995), cannot be maintained, as genera of the Gaultheria group are more closely related to the Vaccinieae than they are to those of the Lyonia group. The strong support for the Lyonia group in the combined analysis indicates that the group should be given formal recognition, and it is here proposed as the tribe Lyonieae—Lyonieae Kron & Judd, tribus nov. Epidermis foliorum lignea; filamenta floris plerumque S-formis; testa cellulis plerumque elongatis. Type genus: Lyonia Nutt. Other nomenclatural proposals relating to these genera will be presented in connection with a new classification of the Ericaceae (Kron et al., unpublished data). The monophyly of the Gaultheria group is not supported in most of the analyses and only weakly supported in the molecular morphology analysis. In the combined rbcL and matK analysis the Gaultheria group is split into two clades that are not resolved with respect to Vaccinieae. Inclusion of the morphological data results in only a weakly supported Gaultheria group. This group needs further study, especially a more comprehensive sampling of Gaultheria, Pernettya, and Diplycosia. In addition, Leucothoë appears as paraphyletic or polyphyletic in most of the trees. Exceptions are in some of the morphological trees and in the rbcL analysis. In both cases the relationship of Leucothoë racemosa to L. fontanesiana is weakly supported. Andromeda, Chamaedaphne, and Oxydendrum often have been considered taxonomically isolated (Palser, 1951, 1952; Stevens, 1969, 1971), but our results support an isolated position for only Oxydendrum (Fig. 6). Andromeda has several distinctive features, which probably represent autapomorphies, e.g., seeds with a strongly multilayered testa, campylotropous ovules (Palser, 1952), the lack of calyx and corolla stomata, and lack of multicellular hairs. The linking of this genus with Zenobia was not anticipated and is not reinforced by any morphological characters included in our analyses. The base chromosome number of Andromeda, i.e., 12, also is aberrant given its placement with genera of the Gaultheria group, which are mainly x 11. However, it may be significant that Zenobia nearly lacks multicellular hairs, i.e., they are only associated with the leaf serrations, and if these were lost (as presumably occurred in the ancestors of Andromeda) then this genus, like Andromeda, would lack such hairs. Chamaedaphne is distinctive in its floral anatomy, embryology, campylotropous ovules (Palser, 1951, 1952), anthers with tubules, and distinctive lepidote indumentum (composed of peltate scales that are different in form from those of Lyonia sect. Lyonia; see Judd, 1979). Both molecular and morphological analyses place Chamaedaphne with members of the Gaultheria group. It is placed sister to Leucothoë racemosa in our combined analysis. Both have stamens with smooth filaments (no. 36-2; see Fig. 4, where feature is homoplasious). Stevens (1969) noted that ‘‘in stomata, bracteole, seed and general anatomical characters it shows some similarity to the Gaultheria group.’’ For example, its stomata are positionally paracytic and testa cells isodiametric. Oxydendrum also is phenetically distinctive, mainly because of its floral anatomy (all traces to the floral organs leave an elongated axis separately; Palser, 1952), deeply hooked leaf midrib vascular bundle (Stevens, 1969, 1971), anthers with terminal tubules, and terminal inflorescence that fruits in the same year in which the shoot on which it is borne was initiated (Lems, 1962). Cox (1948) considered Oxydendrum in its own tribe because its wood has a distinctive medullary ray type and a high percentage of porous vessel perforation plates. Our analyses suggest that these features represent a combination of autapomorphies and retained plesiomorphies. Our results are in general agreement with those of Stevens (1969, 1971), Judd (1979), and Middleton (1991) in supporting the recognition of two major clades within the genera traditionally placed within Andromedeae. Clearly, they also support the hypothesis (see Stevens, 1995) that the Andromedeae are not monophyletic, since Vaccinieae are closely related to members of the Gaultheria group. The close relationship of Vaccinieae to some genera traditionally placed within Andromedeae was first noted by Stevens (1969, 1971), and their phenetic similarity was evident to Watson, Williams, and Lance (1967). Higher level phylogenetic analyses of Ericaceae based on both nuclear and chloroplast DNA (see Kron and Chase, 1993; Kron, 1996, 1997; Kron et al., 1998) support the existence of a clade comprising Oxydendrum, the Gaultheria group, the Lyonia group, and the Vaccinieae, i.e., the ingroup taxa of the analyses herein presented. This monophyletic group, which in large part corresponds to the Vaccinioideae of Stevens (1969), probably should be given subfamilial rank within an expanded Ericaceae
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