The results of the present analysis suggest that the most restrictive description of BambusoideaeXX is a non-monophyletic assemblage. We sampled 72 grass species representing 24 tribes and encompassing all 16 subfamilies proposed in various modern treatments of the family.
SCORING OF STRUCTURAL CHARACTERS AND USE OF EXEMPLAR TAXA
S^hlsmS for mulnspec.es taxa used as terminals should be considered a SS. Cladistic analyzes of a variety of molecular data have been used in previous studies to don ^ ^ T mtemal W0**. The analyzes based on cpDNA gene sequences and restriction sites all estimate the history of the same non-recombining, non-reticulating organ lineage.
In contrast, the Bambusoideae, as recognized in such classifications. arise from elements assigned to Bambusoideae in those classifications (although different Z-ranks are resolved from different datasets). Some elements of a broadly defined Bambuso.deae are resolved within or adjacent to cl.des Pooideae or PACC and these two groups may be expanded in membership to accommodate those separate elements, D.arrheneae and Phaenospermateae Renvoize & Clayton. two fisT "gone". Bambuso.deae by Clayton and Renvoize (1986) or Watson and Da Iwitz (1992) appear to belong m Poo.deae, and one (Cen.otheceae) appears to belong to PACC c d7whi Brachye ytreae are resolved as closely related to Pooideae .
Among the remains of a broadly defined Bambusoideae, the Bambuseae and Oryze.e (the most recently sampled tr.be of this group), plus the Anomoch.oeae, StrepLhae ae Ph.re".
PHYLOGENETIC STRUCTURE OF THE GRASSES 1. Support for Groups Resolved by the Present Analysis
STRUCTURAL CHARACTER EVOLUTION IN THE GRASSES
Spikelets with single fertile flowers occur in early diverging lineages (Phareae) and in almost all later diverging herbaceous lineages (Olyreae, Parianeae, Ehrharta, Oryzeae) before the point of divergence of the Brachyelytrum, Pooideae and PACC clade, and this condition appears to be plesiomorphic in Bambuseae . Thus, the trees and character state distributions in the present results provide some support for Clayton's (1990) interpretation of the evolution of the grass axil, with the caveat that all multiflowered axils found in living grasses in the Bambuseae, Pooideae, and PACC clade may represent reversions, while the plesiomorphic multi-flowered spikelet no. In the PACC clade, above the point where Aristida diverges from other members of the clade, the apical membranous portion is reduced or absent, giving the lodicula a truncated shape and fleshy texture.
Ehrhartoideae is sister to the clade consisting of Brachyelytrum, Pooideae and the PACC clade, and the change from three to two lodicules is a synapomorphy of this set of four genera (Fig. 5). This condition changed to three stamens before the separation of the PACC cladc and Pooideae. Thus, with simple stigmas also present in Anomochloa, Streplochaeta and Pharus, stigmas appear to be simple at the point of origin of the grasses.
Stigmas reveri to the simple condition in Nardus, Sesleria and Sporobolus and in many genera of the clade PACC and Pooideae that were not sampled in this study.
Under any of the Alternative Topologies, broad plumose stigmas arose twice after the divergence of Phareae, and were plesiomorphically simple in Eremttis, or were lost once and then regained in Eremttis. However, Pariana has stigmas that are distinctly plumose, and intros (Hollowell, 1987), the sparsely arranged primary branches arise on the inside of the main axes and are not rebranched, and the receptive cells express papillae only at the branch. hints (pers. obi.). In the phylogenetic structures resolved by simultaneous analysis of the two data sets, stigmas with branches consisting of elongated series of receptive cells arise one or more times in the rest of the grasses (Figure 3, around node 5).
Embryo and caryopsis characters tend to be phylogenetically stable in the grasses. Although characteristic grass features such as spikelets and lodicules may not have been present in the earliest grasses (see above), the grass-like fruit, with a lateral and well-developed embryo (character. The four characters (characters 26–29) of Reeder's embryo formula all provide synapomorphies for the PACC clade and Pooideae, and for subclades within these two main groups. However, they were of little use in determining relationships between these clades and the previously diverged lineages, at least with current sampling, because they are either optimizable at several nodes around the junction of these genera in the most parsimonious trees, or they are apomorphies of genera within the PACC clade or Pooideae.
An elongated linear h.lum (char. 24) is plesiomorphic in grasses iVis characteristic of ,n diverging lines before the PoomTaean^ mfpTrr" H divergence point.
34;^ZcS:^
Presence of cross-venation of the leaf blade (char. 33) appears to be plesiomorphic in the grasses. Bicellular microhairs are present in Anomoohlooideae and are widespread among other early diverging lineages, but are absent in several of the tribes and genera in this region of the phylogeny: Pharus and Phareae [except Suddia Renvoize, which is excluded from Phareae by Judziewicz (1987), and which were not sampled in this study], Ehrharta, Streptogyna and Porteresia (the latter two genera were not sampled). The absence of multicellular microhairs in Brachyelytrum is interpreted as an independent loss under Alternative Topology 2 (PACC clade sister to Pooideae), while under Alternative Topology 1 it may, but need not, be a synapomorphy of the clade that includes Brachyelytrum and Pooi - deae.
This cell type is absent from Brachyelytrum, all Pooideae, and most members of the PACC clade (except Phragmlles during the current sampling and in a few other unsampled genera of Arundinoids, Chloridoideae, and Panicoideae). Current sampling optimizes arm cell loss as a synapomorphy of a clade that includes Brachyelytrum, Pooideae and the PACC clade (Fig. 3, node 13) in any of the alternative topologies, but more extensive sampling within the PACC clade could change this result. Within the grasses, the loss of fusoid cells in alternative topology 1 (early diverging Ehrhartoideae) is a parallel phenomenon in Ehrhartoideae and in the clade that includes Brachyelytnimi, Pooideae and the PACC clade, while in alternative topology 2 (late diverging Ehrhartoideae), it is a synapomorphy of a clade that includes all four of these groups.
C Although stigmas in these living families have short lateral branches in some cases, illustrations of meir stgmaseihs with branches that are not composed of, or do not clearly show, series of receptive cells are illustrated by Baloskion (in Black, 1960). in the later category. For this reason, in our analysis and discussion we have taken up the definition of "fluffy" to stigmatize that I have elongated branches and therefore a non-linear appearance (i.e., states 2 and 3 of Chapter 22). T u Tw, The stigmas of Slreptochaeta and Pharus appear to have been simple where the grasses came from. The occurrence of simple stigmas in certain early diverging herbaceous genera has been interpreted as an inversion of fluffy stigmas (Soderstrom, 1981: 44). However, TarZa arranged the primary branches on the inside of the major axes and has not been banned. The receptive cells express papillae only at the tips of the branches (pers.^s^The on. But TarZa arranged primary branches fit on the inner side of the main axes and are not I banchedLand the receptive cells only express papillae at the branch tips (pers.^s^The on. dition inPar.ana may represent a new state or an intermediate state state between simple stgmas and the more frequent plumose state in grasses Topology 2, the occurring .. resolved Centropodia as sister sroun nf trii, the NAD-ME system arose before PCK.ZleyMdWatson <1992) th*<. Lancet-shaped, membranous, non- or weakly vascularized lodicules are both plesiomorphic and common in Pooideae, and the three-lodicules Zte£ • , -^-^rgmgl^. H °f ?eandbaSCnUmbCr0th• ^°• ta the PACC clade Atagh, most of the above characters are homoplasic in bomb subfamilies, the presence of mis sui of synapomorph,c or plesiomorphic characters of the Pooideae and absence of anv,L• ,. The locations in current phylogenetic trees of transformations in the degree of stigmatic branching, from simple in AnonocMoa, Streptochaeta, Phareae and Parianeae to promotion, suggest corresponding changes among early grasses from insect to wind tussock (Ph. Niklas, 1985), and they are clearly advantageous for wind pollination. Oendrocalamus Nccs, these bamboos tend to be anecdotal about most of the early diverging Cl W * 'Guaranteed. PHYLOGENETICS AND CHARACTER EVOLUTION IN THE POACEAE. self-incompatibility developed only once or twice in Erass^PnrtK. sits only occasionally and Ln onty in gen^^cor ^^ SyStem'" hasbe» demon- peninent literature in Chapman, 1990).Mex <£Z ^ ^^ ^ ~ panb.hty of the system was not determined in oH £ ?' u?0UghthenatUreofthc incom- widely documented in grasses. However, since these two genera only come from the New World and th. s^Amrtoti^is^riSiEsr-r* is spread between. tinents well into the early Terttry S^n f97 Stebbt TSuV "Z'T ^ ^ South America during the Paleocene LJvhvT i }' As^sses arose in. fragments, spikelets with two glumes keeled, two floretIS ' T be lemmas and paleas but are not well preserved. shows the Nation of the structural ie^iiliM^^" Ch,°r°p,aStDNA. PHYLOENETICS AND CHARACTER EVOLUTION IN POACEAE 61. mcongruence in phylogenetic analysis- An ZhZT DM* dec,Siven«S> data quality, and. Biol PiCfr°mthem°n°=°tyIedons with mitochondria. s.ons and the origin of the grass familyZj ?L v MT'J^"ZChloroPlast DNA inver- DUV.I, M. Dioscorides Press, Po.and, Oregon. 1989, The complete chloroplast genome sequence of rice {Oryza smlva)- Intermolecular recombination between separate tRNA genes accounts for a major plastid DNA in^. version dunngthe evolution of cereals. Handbook of herbs of the United States. eds.), Vascular Plants of the Pacific Northwest. Taxonomic patterns in protein amino acid profiles of grass leaves and caryopsis. eds.), Grass systematics and evolution Smithsonian Institution Press, Washington, DC. Systematics of the subtribe Parianinae (Poaceae: Bambuseac- Olyrcae) PhD thesis, University of South Carolina, Columbia ' Holmgren, A. Substitution rate comparisons between grasses and palms: Synonymous rate differences at the nuclear gene Adh parallel rate differences at plastid genericL. Estimation of character weights during tree search. I1SISSH H f T2 el°n8atePapiI'aterCCeptiveCeIIs' orwi* very short branch composed of a few papillate receptive cells, but in the latter case the .tioJ.,. S . ancient); 2 - primary (branches well developed, c^~0fS«TdiS pap leaves receptive eel s, secondary branches absent or minimally developed dX masil«oeol«eorbn,ader);3-5econd«y(,coond«y welded to tertiary branches ped, branches composed of series of scattered papillate receiving cells NOTE. Appendix 3: Structural Character Data GENERAL SSe'-S^^ LITERATURE CITED Authors are encouraged to contact the editor (THE BOTANICAL REVIEW Scinc title Publications Department, The New York Botanical Garden, Bronx, NY US A) whenever a paper has any special requirements not addressed in the following guidelines. 3-^SmS^^SaS=^^
Acknowledgments
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SAMPLES OF LITERATURE CITED
