The Plant Press

New Faces

From Plant Press, Vol. 28, No. 1, January 2025.

Danielle Remor (center) with Carol Kelloff and Warren Wagner

Danielle Remor is a Brazilian Ph.D. student in Botany at the State University of Feira de Santana (UEFS) and was awarded the 2024 Harold E. Robinson and Vicki A. Funk Award. Remor has been working with the Asteraceae family since her Master's degree. Her Ph.D. thesis aims to use integrative taxonomy to produce a phylogeny through phylogenomic methods for the genera Caatinganthus, Mattfeldanthus, Stilpnopappus, Strophopappus, and Xiphochaeta, which compose the Stilpnopappus alliance (Asteraceae, Vernonieae). Furthermore, she seeks to provide an updated taxonomic review and investigate, through biogeography, how these genera colonized the dry regions of Brazil. The U.S. National Herbarium houses a large number of collections of this group, including important Venezuelan specimens and type materials. During her one-month visit to the National Herbarium in October, supervised by Warren Wagner with assistance from Carol Kelloff, Remor was able to analyze and review the morphology of all morphotypes belonging to her study group, including relevant type specimens. The opportunity to visit the herbarium allowed her to access materials she had not yet been able to describe, significantly contributing to and expanding the results of her taxonomic review and updating the taxonomic identity of various materials. She also acquired samples from 10 species for DNA extraction, which will contribute to an overview of the taxonomic and evolutionary relationships of the genera in the Stilpnopappus alliance, providing valuable insights for the Vernonieae tribe.

Rose Villanueva (left) with Jun Wen, Tina Wang, and Yali Li.

Rosa María Villanueva Espinoza, a Master’s student in Botany at the South China Botanical Garden, was awarded a 2024 José Cuatrecasas Award. She visited the National Herbarium from October 7 through November 5, under the supervision of Jun Wen to study, “Taxonomy and phylogeny of the genus Justicia (Acanthaceae: Justicieae: Justiciinae) in Peru.” During her visit, Villanueva determined the species rank of various unidentified and misidentified Justicia specimens, some of which represent new taxa. In addition, she examined Justicia collections from other countries to help document the occurrence of Justicia boliviensis in Peru, constituting a new record for the country. Type collections and additional specimens from closely related species, such as J. inficiens, J. pilosa, J. lancifolia, and J. obovata, were revised. The revision of the US collection further elucidated the morphological similarities between J. wallnoeferi and J. cuscoensis. She also photographed diagnostic features such as stamens, seeds, and fruits of Peruvian species to enhance her Master's project. Furthermore, leaf fragments from 31 Justicia species were collected for future phylogenetic studies within this genus. Some of these findings, including new species and nomenclatural novelties, have already been included in a submitted manuscript to Phytokeys. A second paper, currently in progress, integrates the additional data obtained from the US and her revisions undertaken from various other herbaria.

Peanut illustration used to honor President Carter

From Plant Press, Vol. 28, No. 1, January 2025.

When Jimmy Carter (1924-2024) passed away on December 29, 2024, the Smithsonian's National Museum of Natural History used social media to honor him.

To mark his passing and to recognize that Carter rose from Georgia peanut farmer to the 39th president of the United States, the museum used an illustration of a peanut plant (Arachis hypogaea), which was drawn by Department of Botany illustrator Alice Tangerini.

The illustration was drawn in 1975 at the request of Edward Ayensu who included it in his article, “Africa in the American Presence,” a paper from the international conference The United States in the World held in 1976 in Washington, DC.

Illustration of a peanut plant (Arachis hypogaea) by Alice Tangerini.

Untangling Trebouxia, a green algal lichen photobiont in southern Africa

From Plant Press, Vol. 28, No. 1, January 2025.

By Ian Medeiros.

A recent study in the American Journal of Botany (2024; https://doi.org/10.1002/ajb2.16441) provides a first view of the southern African biodiversity of the green algal genus Trebouxia (Chlorophyta), the most common photosynthetic partner in lichens.

Trebouxia in a squash preparation of lichen thallus. Hale 78605 (US).

Southern Africa, particularly the Greater Cape Floristic Region, is a biodiversity hotspot for vascular plants and hosts a unique biota of lichen-forming fungi (mycobionts). However, the region’s lichen-forming algae (photobionts) had hardly been studied with molecular data or put into a global phylogenetic context. In the unicellular green alga Trebouxia, as with other lichen photobiont lineages, genomic variation far exceeds the limited morphological variation, and thus molecular data are essential for recognizing species.

To begin the process of applying a modern classification scheme to Trebouxia in South Africa and Namibia, an international team of scientists from the United States, Belgium, Chile, Hungary, Malaysia, Namibia, Panama, Poland, and South Africa sequenced the internal transcribed spacer (ITS) and rbcL from ca. 150 lichen thalli representing diverse mycobionts and biomes, from desert and fynbos to Afrotemperate forest and montane grassland. These sequences were incorporated into curated, global datasets; putative species were delimited with both phylogeny and operational taxonomic unit (OTU) clustering approaches as a way of ensuring that conclusions were robust to uncertain species boundaries.

We found that the Trebouxia biota of this region contains an estimated 43 species, representing 20–30% of global Trebouxia biodiversity. This is comparable to other well-sampled regions of the Southern Hemisphere (i.e., Bolivia and Kenya). On one hand, the results exemplify an “everything is everywhere” approach to microbial biogeography, with a majority of the southern African Trebouxia species shared with Bolivia, Kenya, or the Mediterranean basin. Conversely, seven species were only found in southern Africa, although further sampling will be required to assess whether they are truly southern African endemics.

Sampling for lichen photobionts in the northern mistbelt forest of the Buffelskloof Nature Reserve, South Africa. (photo by József Geml)

Patterns in species distribution and the mycobiont–photobiont association echoed what has been found elsewhere in the world. For example, the foggy Namib desert coast was dominated by species of Trebouxia clade A, something also seen in the Atacama Desert of Chile. The mycobiont genus Parmotrema was strictly associated with species from Trebouxia clade C, as has been observed in the Neotropics and Northern Hemisphere. Mean annual precipitation, but not mean annual temperature or precipitation seasonality, was found to have a significant effect on the composition of Trebouxia communities.

Only five of the species-level lineages recognized in this study have been formally described, highlighting the substantial Linnean shortfall in Trebouxia, but also providing a blueprint for future efforts to recollect, culture, and formally describe these species.

A new grass family phylogeny is published

From Plant Press, Vol. 28, No. 1, January 2025.

A collaborative effort from the Grass Phylogeny Working Group III has resulted in the publication of a new grass phylogeny inferred from 331 nuclear genes for more than 1,100 grass species entitled, “A nuclear phylogenomic tree of grasses (Poaceae) recovers current classification despite gene tree incongruence” (New Phytologist, https://doi.org/10.1111/nph.20263). The international team of 74 scientists, including the Smithsonian Institution’s Paul Peterson and Rob Soreng, provide a corrected framework for revising the grass tree of life, which will support further research into grass evolution.

Phylogeny of 1153 Poaceae accessions inferred from 331 nuclear genes. (Image from New Phytologist, https://doi.org/10.1111/nph.20263)

The grass family has nearly 11,800 species in 791 genera, 109 subtribes, 54 tribes, 7 supertribes, and 12 subfamilies (Soreng et al., 2022; https://doi.org/10.1111/jse.12847; classification posted on TROPICOS). Poaceae is among the largest plant families of the world and is widely used by humans for food (rice, corn, wheat), building materials (reed, bamboo), and biofuels (sugarcane, switchgrass). Knowing the evolutionary history of this important plant family and how the taxa are related will help advance comparative biological research, the impact of hybridization, studies in crop breeding, understanding biodiversity and ecosystem conservation, and improve our classification among the subfamilies, tribes, subtribes, and genera.

The newly published nuclear DNA tree covers 79% of grass genera. Herbarium specimens were used to sequence 21 rare genera and one hybrid for the first time (Pharoideae: Scrotochoa. Bambusoideae: Ekmanochloa, Fimbribambusa, Miniochloa, Parabambusa, Pinga, Ruhooglandia, Widjagachloa. Pooideae: Agropyropsis. Panicoideae: Asthenochloa, Bhidia, Dilophotriche, Hydrothauma, Oryzidium, Pogonachne, Pseudodichanthium, Thedachloa, Thyridachne, Trilobachne. Chloridoideae: Kampochloa, Pommeruella, × Cynochloris), confirming or fine-tuning their classifications.

The gene set was leveraged from five diverse sets of genomic data: (1) 450 Illumina target capture read accessions enriched with the Angiosperm353 probe set; (2) 295 Illumina shotgun whole-genome sequencing accessions; (3) 17 Illumina target capture read accessions enriched with 122 nuclear loci; (4) 343 assembled transcriptomes assembled from two recent studies; and (5) 48 whole genome sequences from PHYTOZOME v.13. The nuclear gene tree topology was compared to plastome regions by a 910-tip tree using the sequences of 70 coding plastome regions and the trnL‒trnF intergenic region. Evidence for reticulations (hybridization, introgression, and lateral transfers) was investigated using gene tree‒species tree reconciliation methods. Supported conflicts at the tribal level were detected for five genera; plastome data was not included for three other genera that resolved in different tribes than previously classified in Soreng et al. (2022). These conflicts need further study.

The timeline of grass evolution continues to be a hot topic among agrostologists, and this new phylogeny supports earlier biogeography studies (Gallaher et al., 2022; https://doi.org/10.1111/jse.12857) suggesting the Poaceae began to diversify in the early–late Cretaceous (crown age of 98.54 Ma) on West Gondwana before the complete split between Africa and South America. Africa clearly served as the center of origin for much of the early diversification of the lineages within the family.