Amy Jean Gilmartin

Stigma structure and variation in Bromeliaceae—Neglected taxonomic characters

Three distinct types of stigma architecture, designated as “simple-erect,” “conduplicate-spiral”, and “convolute-blade” were identified for Bromeliaceae. Structure of the conduplicate-spiral and convolute-blade stigma types is highly complex and previously unreported. Stigma morphology, largely neglected in Tillandsioideae until recently, promises to yield new characters valuable in interpreting systematic relationships in this subfamily. Data indicate that the putatively plesiomorphic state (simple-erect) is retained in some members of all three subfamilies. We found convolute-blade-type stigmas only in Tillandsioideae, though not in all members of the subfamily. Our sample indicates that Tillandsioideae stigmas are more like those of Pitcairnioideae than of Bromelioideae, which is consistent with Smith’s hypothesis of phylogenetic proximity of Tillandsioideae and Pitcairnioideae. Stigma architecture is proving to be a rich source of data for phylogenetic reconstruction and for classification at several infrafamilial levels.

Subfamilial Phylogenetic Relationships of the Bromeliaceae: Evidence from Chloroplast DNA Restriction Site Variation

Restriction-site analyses of the chloroplast genomes of members of the Bromeliaceae were conducted to explore subfamilial phylogenetic relationships. Eighteen restriction-site muta- tions and one large (1.8-kb) length mutation were found to be variable at the family and subfamily levels. Cladistic analyses of these data supported the following hypotheses: 1) Bromelioideae and Pitcairnioideae are sister taxa and the latter may be paraphyletic; 2) Tillandsioideae s. str. and Bromelioideae are each monophyletic; 3) Tillandsioideae s. str. is the sister taxon of the remainder of the family; and 4) Glomeropitcairnia is phylogenetically distinct from the remainder of Tilland- sioideae. These analyses suggest that the primarily terrestrial Pitcairnioideae are not basal in the family even though the terrestrial habit apparently is ancestral in Bromeliaceae. Chloroplast DNA data also support the contention that some morphological characters have evolved independently several times in this large, ecologically complex family.

Evolution of Mesic and Xeric Habits in Tillandsia and Vriesea (Bromeliaceae)

Species of Tillandsioideae are usually epiphytic and portray a range of habits from st.rongly xeric with thick, narrow leaves that are densely covered with conspicuous, shield-shaped, moisture-absorbing trichomes to mesic with broad, thin leaves having few and inconspicuous trichomes. Phenetic groupings and evolutionary tree construction of the nine subgenera of Til- landsia and Vriesea and of the 36 species of T. subg. Phytarrhiza by means of cluster analysis, Wagner network, and character compatability, show subgenera with the xeric and mesic habit on the same major branches and with T. subg. Allardtia in an ancestral position on the subgeneric tree. Of the 36 species of T. subg. Phytarrhiza, the 17 of xeric habit are largely on separate branches and the five species of mesic habit, mostly Ecuadorian, are centrally located on the evolutionary tree between the xeric and the 14 semi-mesic species. A phenogram based on 43 characters and portraying overall similarity supports the separation of most of the xeric from the mesic species on the Phytarrhiza tree. The xeric and semi-mesic habits seem to have evolved several times; initially during evolu- tionary differentiation that we recognize at the generic and subgeneric levels. Xeric and semi-mesic species follow mesic ones on each of several different branches of the Phytarrhiza tree. Pleistocene climatic history in South America helps to explain the repeated evolution of species with the xeric habit. During the past decade, we have come to recognize from paleoclimatological studies in South America that the Quaternary climate, especially in upland areas, has undergone a series of humid and xeric phases. Such would have alternately favored evolution of xeric and mesic bromeliads and this seems to have occurred.

Morphological Variation and Speciation

Developmental factors (e.g., canalization, plasticity, epistasis) weaken the integration of genomic and morphological diversification. Numerous non-lethal morphological mutations and several cases of substantial morphological differentiation associated with negligible isozymic di- vergence have been documented. These observations suggest that evolution of plant form often may be punctuational. Patterns of morphological variation observed within and among plant pop- ulations indicate that morphology can diverge in apparently random directions. A comparison of characters in which intraspecific (racial) and interspecific divergence has occurred suggests that adaptation, which is frequently an important component of ecotypic differentiation, may often be a less important factor in speciation. These observations converge to suggest that the differentiation of morphological plant species is frequently rapid and random in direction.

Status of Glomeropitcairnia within evolutionary history of Bromeliaceae

The genus Glomeropitcairnia has long been poorly understood. It has been placed variously within the bromeliad subfamily Tillandsioideae along with five other recognized tillands- ioid genera (Catopsis, Guzmania, Mezobromelia, Tillandsia, and Vriesea); in its own tribe of the tillands- ioid subfamily; and, alternatively, has been considered to be a subgenus within Pitcairnia (subfamily Pitcairnioideae). New data on chromosomes and stigma architecture provide, respectively, plesio- morphies and autapomorphies relative to the familys sister taxon. All available data including morphology and anatomy, as well as the cladistic analysis, support retention of Glomeropitcairnia within subfamily Tillandsioideae and suggest that the genus is sister taxon to the most recent common ancestor of the tillandsioid genera, Guzmania and Mezobromelia.

Cladistic Tests of Hypotheses Concerning Evolution of Xerophytes and Mesophytes Within Tillandsia Subg Phytarrhiza (Bromeliaceae)

Tillandsia L. Subg. Phytarrhiza (Visiani) Baker (Bromeliaceae) is a distinctive group of about 35 epiphytic species. These exhibit a range of habits from xeric to mesic. The evolutionary relationships of the contrasting adaptations need to be established here as well as in the subfamily as a whole. Relations between the subgenus and other tillandsioids are problematical and phylogenetic reconstruction of its member-species would be facilitated by identification of Phytarrhizas relative (sister taxon) sharing the same most recent common ancestor with Phytarrhiza. This paper examines the two most likely sister taxa, Subg. Pseudo-Catopsis Baker and Subg. Diaphoranthema (Beer) Baker. Diaphoranthema is rejected as sister taxon. The accepted evolutionary tree, rooted by Pseudo-Catopsis, indicates that most habital evolutionary changes in Phytarrhiza have been between mesic and semi-mesic forms and from mesic to xeric forms. Methods developed for testing specific evolutionary hypotheses are broadly applicable.

Variability within and among populations of four grass species

The importance of morphological variation for evolutionary and phylogenetic stud- ies is well recognized. This paper concentrates on morphological differences within and among population samples of several species of grasses to interpret potential for further differentiation. Analysis of gross morphology, a traditional tool of systematics, is coupled with numerical taxonomy to identify kinds of morphological differentiation among populations of species of four steppe grasses: Bromus japonicus, B. tectorum, Poa secunda, Pseudoregneria spicata. Floral and vegetative vari- ation in Poa secunda is consistent with apomictic differentiation. Floral characteristics in this species were responsible for more phenotypic divergence between populations (71%) than within popu- lations (35%), while vegetative traits were responsible for 29% of total variance between populations and 65% within populations. Inbreeding in the two Bromus species is not associated with any notable morphological differentiation between populations. Bromus tectorum appears to retain mor- phological uniformity throughout the area sampled. Character states for Pseudoregneria spicata ex- hibit varying degrees of plasticity depending on the population. This comparative study, concerned with differences and similarities in amounts and kinds of variation of morphological traits, repre- sents a first attempt to assess how morphological variation can be examined to detect the potential for some kinds of speciational events.

A New Species of Tillandsia (Bromeliaceae) from Northwest Argentina

A new species, Tillandsia (subg. Anoplophytum) guasamayensis (Bromeliaceae) from northwest Argentina is described and illustrated. Included are keys to a group of five, putatively related taxa within the subgenus. The new species differs from others in the strikingly purple floral bracts of intermediate size (3.0-3.5 cm long), the white petals to 4.0 cm long, and sepals that are 1.8 to 2.5 cm long. Tillandsia subg. Anoplophytum (Beer) Baker, an epiphytic/saxicolous taxon based in eastern South America (e.g., Castellanos 1945; Smith 1943), includes 34 species in the view of Smith and Downs (1977). Recent field research by one of us (Palaci) revealed the presence of a new species in this subgenus, having dark purple floral bracts, white petals, and sepals 1.8 to 2.5 cm long; i.e., features unlike those of any pu- tatively closely related anoplophyton species, such as T. friesii Mez. The plant grows near Til- cara, Jujuy, along the rocky banks of the Rio Guasamayo, together with Abromeitiella lorentz- iana (Mez) Castell, T. diaguitensis Castellanos (see note following description), T. capillaris Ruiz Lopez & Pavon, and species of cactus. The floral bracts are distinctive from T. friesii (known, for example, from the adjacent state of Salta at Que- brada del Toro, 100 km from the collection site of the new species, Fries 828 (S, TYPE), and from

Morphological Variation within Five Angiosperm Families: Asclepiadaceae, Bromeliaceae, Melastomataceae, Piperaceae, and Rubiaceae

Populations of species of four families of Angiosperms were sampled in Colombia in order to quantify variation within and among populations of the same and different species within each family. Variation estimates are also compared to results with Asclepiadaceae sampled from western North America. As sampled, Melastomataceae differ significantly from Piperaceae at the family level and from Rubiaceae at the population level. Melastomataceae shows the greatest range of variation from population to family of any of the six families and Bromeliaceae has nearly as great a range. The extent of variation for Rubiaceae and Piperaceae is much less. Variation within populations of Asclepiadaceae from North America resembles that for Melastomataceae. Explanations for the lower variability and extent of variability of Rubiaceae and Piperaceae rest upon population biology theory. Recent studies of variation within and among populations have fo- cused upon enzymes, and immunological, cytological, chemical, and, es- pecially, morphological characters. Among goals of variation studies em-

Recent collections of Bromeliaceae from Colombia

Guzmania cabrerae from Colombia is described and illustrated. Specimens of three other species which were rarely or never before collected in Colombia are cited.