The Plant Press

Diving into the green algae of Puerto Rico

From Plant Press, Vol. 26, No. 2, April 2023.

A new taxonomic study of the benthic species of green algae known from Puerto Rico has recently been released. “The marine benthic algal flora of Puerto Rico, II. Chlorophyta and Prasinodermatophyta” by David L. Ballantine, James N. Norris, and Hector Ruiz was published in Smithsonian Contributions to Botany, No. 117.

Illustration of Udotea flabellum, a benthic algal species generally found in sandy, shallow-water habitats to 10 m depths as well as in offshore algal plains throughout the Caribbean Sea.

This treatment covers the two phyla, eight orders, 25 families, 50 genera, and 150 species of green algae that occur in the benthic marine communities in Puerto Rico. The study includes information on type locality, distribution, habitat, descriptive accounts of anatomy, taxonomic status, and an image or illustration of most species. One feature of this series that stands out is the quality of illustrations due to many in situ habit photos by co-author Ruiz.

Puerto Rico is the eastern-most island of the Greater Antilles and defines the northern boundary of the Caribbean Sea, thus the north coast borders the Atlantic Ocean while the remaining coasts face the Caribbean.

The marine algal flora of Puerto Rico has been intensively studied, with reports dating back to the 1800s, and has the best-known algal flora of any island or island group in the region. This is especially true of its deep-water flora that has been the subject of extensive exploration by submarine, dredging, scuba, and technical diving. David Ballantine spent most of his 37-year professional career teaching and studying algae as a professor at the University of Puerto Rico, and his long-time collaborators James Norris (curator emeritus NMNH) and Hector Ruiz (HJR Reefscaping, an environmental consulting group) are coauthoring an entire series including brown, green, and red algae.

This volume represents the second installment of the expected four-part series. Parts I and II feature the brown algae and green algae, respectively. The red algae are an especially large and diverse group; thus, Part III will be issued in two volumes.

A new genomic resource available for Annonaceae

From Plant Press, Vol. 26, No. 2, April 2023.

Cherimoya (Annona cherimola) has been an appreciated food source since Pre-Columbian times in the Americas. Although it is currently considered an underutilized fruit crop, it is still important at the local level in several regions of Central and South America. It is commercially cultivated in several countries such as Chile, Ecuador, Peru, Spain, and USA (California), among others, and has a clear niche for expansion in regions with subtropical climates. It belongs to the Annonaceae, the largest family on the Magnoliid clade, sister to the eudicot and monocot clades of angiosperms. But, unfortunately, the progress on cherimoya breeding is hindered by the little genetic and genomic information available, which is a critical bottleneck for breeding, selection, diversification, conservation, and evolutionary studies not only of cherimoya but also in other species in the Annonaceae.

Annona cherimola tree, flower, and fruit morphology. (a) Pruned tree; (b) leaves; (c) female stage of the flower; (d) male stage of the flower; (e) fruit; (f) open fruit. (photos by Alicia Talavera; images from Plants People Planet, doi:

In a recently published paper in Plants People Planet (doi: 10.1002/ppp3.10366), Smithsonian Botany postdoctoral fellow Alicia Talavera, researchers Noé Fernandez-Pozo, Antonio J. Matas Arroyo, and professor Iñaki Hormaza from Instituto de Hortofruticultura Subtropical y Mediterránea La Mayora (IHSM La Mayora-UMA-CSIC), Málaga, Spain in collaboration with Aureliano Bombarely from Instituto de Biología Molecular y Celular de Plantas, IBMCP (CSIC-UPV), Valencia, Spain have provided an important resource to fill this knowledge gap, a chromosome-scale genome sequence, which is available at the IHSM subtropicals database, https://ihsmsubtropicals.uma.es/easy_gdb/index.php.

A look at the Guiana Shield plant collections of Redden and Wurdack

From Plant Press, Vol. 26, No. 2, April 2023.

For more than 30 years, the Biological Diversity of the Guiana Shield (BDG) studied, documented, and preserved the biological diversity of the Guiana Shield in northern South America, which comprises parts of French Guiana, Suriname, Guyana, and Venezuela. The BDG program resulted in numerous publications, and a recently produced publication documents a decade of specimen collections by former and current Smithsonian botanists Karen Redden and Ken Wurdack. The open access publication written by Carol Kelloff, Karen Redden, Ken Wurdack, and Sara Alexander (Smithsonian Contribution to Botany, no. 116) is available for download at https://doi.org/10.5479/si.21912828.

On "Palm Mountain" in October 2008. Left to right: Claudius Perry, Nigel John, Pads Ragnauth, Karen Redden, Elvis Joseph, and Ken Wurdack. (self-timed photo)

In 2006, Vicki Funk asked Redden and Wurdack, who had met in the U.S. National Herbarium the previous year, if they would conduct a joint collecting expedition for the BDG. The BDG had maintained a full- or part-time resident collector in Guyana from 1986 until 2000, after which point it sponsored regular collecting expeditions to locations across the Guiana Shield. Redden and Wurdack’s first trip in 2006 was followed by 16 more (5 jointly plus additional expeditions by Redden with others), in a collaborative partnership that would last until the BDG’s final expedition in 2014.

Progress in taxonomy and evolution of the licorice family

From Plant Press, Vol. 26, No. 1, January 2023.

-Adapted from the Chinese Academy of Sciences

Plants in the genus Glycyrrhiza (Fabaceae) are an important biological resource and one of the bulk of traditional Chinese medicinal materials. Its medicinal functions have been known in many countries in Asia, Africa, and Europe since ancient times. The medicinal licorice species of this genus contain a variety of secondary metabolites, among them glycyrrhizic acid and liquiritin, which have the effects of eliminating phlegm and relieving cough. Glycyrrhiza and Glycyrrhizopsis make up the tribe Glycyrrhizeae. At present, the classification of this tribe is controversial, which affects its application to a certain extent.

Flower and fruit morphologies of three varieties of Glycyrrhiza glabra. Flowers (upper left) and fruits (upper right) of Glycyrrhiza glabra var. glabra; fruits of G. glabra var. uralensis lower left); and fruits of G. glabra var. inflata (lower right). (image from J. Syst. Evol. doi: 10.1111/jse.12902)

In a newly published study, researchers extracted low-copy nuclear genes from genome shallow sequencing data, built trees together with chloroplast genome and ribosomal DNA, and combined morphological and specimen image recognition technologies for classification and phylogenetic research. The study found that the genus Meristotropis endemic to Central Asia should be merged into the genus Glycyrrhiza, so the genus contains 13 species; while its sister group Glycyrrhizopsis is endemic to the West Anatolian Plateau and only contains two species.

Nature editorial connects the dots between forests, models, and funding

From Plant Press, Vol. 25, No. 4, October 2022.

A Nature editorial (608: 449; 2022) contends that it is well-past time to fund forest science like our future depends on it, stating, “Forests are our life-support system, and we should be more serious about taking their pulse.”

Forest systems store about half of the world’s carbon. They also take up 25% of all new anthropogenic carbon emissions; but can we expect them to continue doing so as climate change intensifies? Dynamic global vegetation models are our best way of anticipating the answer. They are also incredibly difficult to create due to the complexity of forest systems and the limits of drawing upon studies that were conducted at single forest sites.

Map from Dow, et al. (2022) depicting sampling locations of tree-ring chronologies analyzed in the study. Sites are colored by the xylem porosity type of species sampled: ring porous (RP), diffuse porous (DP), or both.

A new Nature paper by Dow, et al. (608: 552-557; 2022) uses dendrometer data from Harvard Forest and Smithsonian Conservation Biology Institute Forest Dynamics Plots, plus tree-ring records from 108 forests across the eastern US to examine the impact of warmer springs on carbon sequestration capacities of forests. Contrary to the expectations of many vegetation models, the data from Dow, et al. indicates that warmer springs do not lead to increased wood growth. Consequently, current vegetation models are overestimating the capacity of forests to mitigate climate change. This paper was lead-authored by Cameron Dow who began this manuscript with colleagues during his internship in Kristina Anderson-Teixeira’s ForestGEO Ecosystems & Climate Lab.

New issue of the Journal of Systematics and Evolution investigates the biogeography and phylogenetics within the grasses

From Plant Press, Vol. 25, No. 4, October 2022.

Paul Peterson and Robert Soreng organized and published (with help from Konstantin Romaschenko) a complete issue of the Journal of Systematics and Evolution [60(3): 473-712; 2022 https://doi.org/10.1111/jse.12776] investigating the biogeography and phylogenetics within the grasses. Using the fossil record to aid in dating their phylogenetic trees and combining molecular sequence studies of DNA, they reconstructed ancestral states to infer the origin of major clades; i.e., subfamilies, tribes, supersubtribes, subtribes, and selected genera in the grasses. For this special issue, Peterson and Soreng invited a broadly trained group of 35 scientists to collaborate and present their most recent advances culminating in 10 publications.

Phylogenetic reconstruction and timetree of the Poaceae and close relatives (Joinvillea, Ecdeioclea, and Flagellaria) based on chloroplast DNA sequence from 700 samples, as seen in Gallaher, et al. (2022). The branches are color-coded by subfamily and collapsed at the subtribal level. Nodes with posterior probabilities below 0.99 are marked with a white node symbol and the posterior probability is shown. Node bars represent the 95% highest posterior density of node age estimates.

Four of the manuscripts in the issue include new dated biogeographical analyses (Gallaher et al., 2022; Peterson et al., 2022b; Soreng et al., 2022a; Zhou et al., 2022); three comprise new phylogenetic analyses with novelties (Da Silva et al., 2022; Peterson et al., 2022a, 2022c), one is an ecological study investigating functional traits in a clade of savanna/wetland grasses (Arthan et al., 2022), one looked at the current distribution of the grasses over the Australian continent to determine migration directionality (Bryceson & Morgan, 2022), and one is an updated classification of the family primarily based on molecular phylogenetic studies (Soreng et al., 2022b).

Lost South American wildflower named “extinctus” rediscovered (but still endangered) [Video]

From Plant Press, Vol. 25, No. 3, July 2022.

-Adapted from the Field Museum.

Scientific names get chosen for lots of reasons-- they can honor an important person, or hint at what an organism looks like or where it’s from. For a tropical wildflower first described by Smithsonian Botanist Laurence Skog and his colleague Lars Kvist in 2000, the scientific name “extinctus” was a warning. The orange wildflower had been found 15 years earlier in an Ecuadorian forest that had since been largely destroyed; Skog and Kvist suspected that by the time they named the species, it was already extinct (Syst. Bot. Monogr. 59: 1-118; 2000; https://doi.org/10.2307/25027883). But in a new paper in PhytoKeys (https://doi.org/10.3897/phytokeys.194.79638), researchers report the first confirmed sightings of Gasteranthus extinctus in 40 years.

The bright orange flowers of the Ecuadorian cloud forest herb Gasteranthus extinctus, a species once long believed to have gone extinct. (photo by Riley Fortier)

“Extinctus was given its striking name in light of the extensive deforestation in western Ecuador,” says Dawson White, a postdoctoral researcher at Chicago’s Field Museum and co-lead author of the paper. “But if you claim something's gone, then no one is really going to go out and look for it anymore. There are still a lot of important species that are still out there, even though overall, we're in this age of extinction.”

Specimen collected by Smithsonian botanist in the 1920s determined to be a new species nearly a century later

From Plant Press, Vol. 25, No. 2, April 2022.

By Jerald Pinson (Florida Museum of Natural History)

A plant specimen that had been collected in northwestern Haiti in 1929 by Smithsonian botanist E.C. Leonard has led researchers from the Florida Museum of Natural History to the discovery of a new plant species, Castela senticosa, which they recommend be designated as endangered. The plant, which grows as a small bush sheathed in an imposing layer of spines, was recently found during a survey to catalog the flora of the Martín García mountain range in the Dominican Republic and compared to the Leonard specimen.

Castela senticosa produces flowers and fruit at the tail-end of the dry season, when most other plants are still dormant. Although risky, this allows them to stand out to pollinators and dispersers that might otherwise miss them in the dense vegetation common during the rainy season. (photo courtesy of Systematic Botany)

“We were collecting everything we came across with the goal of having a complete species list for the entire mountain range,” said lead author Lucas Majure, an assistant curator at the Florida Museum of Natural History and curator of the University of Florida Herbarium.

Hispaniola’s mountains support large swaths of intact tropical dry forests, highly diverse ecosystems that — like the rainforests they border — are globally imperiled due to the combined effects of deforestation, overharvesting and climate change. But although they face the same threats, the destruction of a tropical dry forest might mean the loss of considerably more species. That’s because rainforests are often found in lowland basins, where conditions like rainfall, temperature and soil type are similar over large areas. While species diversity is high, many rainforest plants can have distributions that span hundreds of miles.

Ancient hybridization and genome doubling explain the origin of the apple tribe

From Plant Press, Vol. 25, No. 2, April 2022.

In the 1930s, biologists studying chromosomes in the rose family (Rosaceae) noticed that species in the apple tribe (Maleae) had approximately twice as many chromosomes (base chromosome number = 17) as every other species in the rose family (base chromosome number = 7, 8, or 9). Over the ensuing decades, researchers proposed hypotheses of hybridization and/or genome doubling to explain the evolutionary origin of the apple tribe and the unusually high chromosome counts in the apple tribe.

There were two competing hypotheses explaining the evolutionary origin of the apple tribe, but it was difficult to test them rigorously with the data available at the time. For many years, botanists tested these hypotheses using morphological characters, chromosome count data, and more recently, single-locus genetic data. Until a few years ago, researchers did not have access to genome-scale genetic data to test hypotheses of ancient hybridization and/or genome doubling.

An ancient hybridization event gave rise to the apple tribe (Maleae) in the rose family, Rosaceae. Maleae taxa include (from left) sweet crabapple (Malus coronaria), Callery pear (Pyrus calleryana), and Canadian serviceberry (Amelanchier canadensis). (photos by Richie Hodel and Jun Wen)

Smithsonian scientists Richie Hodel, Liz Zimmer, Bin-Bin Liu, and Jun Wen synthesized recently published phylogenomic data from the nuclear and chloroplast genomes of multiple species in the rose family, and applied novel phylogenetic network and multiply-labeled tree analyses to resolve the origin of the apple tribe. They found that an ancient hybridization event occurred between ancestors of the Rosaceae tribes Sorbarieae and Spiraeeae, likely between approximately 65-50 million years ago. Phylogenetic network analyses indicated this hybridization event gave rise to the clade Gillenieae + Maleae. The tribe Gillenieae is a small clade with follicular fruit sister to the larger pome-bearing apple tribe. In contrast to the Maleae, the Gillenieae do not have elevated chromosome counts, indicating that this hybridization event promoted the diversification of the clade Gillenieae + Maleae, but does not explain the high chromosome number in Maleae.

Another key result was that subsequent allopolyploidy (genome doubling involving two distinct species) between ancestors of the apple tribe likely occurred between approximately 50-35 million years ago. Multiply-labeled tree analyses indicated this event probably followed the divergence of the Gillenieae and Maleae lineages. This genome doubling event explains the elevated chromosome numbers observed in the Maleae by researchers over the past century. The research is published in Frontiers in Plant Science (https://doi.org/10.3389/fpls.2021.820997).

Rosaceae tribe, Amygdaleae, which includes (from left) Japanese apricot (Prunus mume) and almond (Prunus dulcis), was once hypothesized to have played a role in a hybridization event leading to the apple tribe, but recent research indicates the participants in the ancient hybridization event were likely ancestors of the tribes Spiraeeae and Sorbarieae. (photos by Richie Hodel and Jun Wen)

Explosive fossil fruit found buried beneath ancient Indian lava flows

From Plant Press, Vol. 25, No. 2, April 2022.

-Adapted from Jerald Pinson (The Florida Museum of Natural History).

Just before the closing scenes of the Cretaceous Period, India was a rogue subcontinent on a collision course with Asia. Before the two landmasses merged, however, India rafted over a “hot spot” within the Earth’s crust, triggering one of the largest volcanic eruptions in Earth’s history, which likely contributed to the extinction of the dinosaurs.

In a recent study published in the International Journal of Plant Sciences (183: 128-138; 2022 https://doi.org/10.1086/717691) scientists excavating the fossilized remains of plant material wedged between layers of volcanic rock describe a new plant species based on the presence of distinctive fruit capsules that likely exploded to disperse their seeds. The fossils may be the oldest fruit discovered to date of the spurge family (Euphorbiaceae), a group of plants with more than 7,000 species, with well-known representatives that include poinsettia, castor oil plant, rubber trees, and crotons.

The fruit of Euphorbiotheca deccanensis is potentially the oldest ever discovered of the spurge family (Euphorbiaceae). Based on the preserved fibers within the fossilized fruit, researchers think it likely exploded to disperse its seeds. (photo by Kristen Grace, Florida Museum of Natural History)

The fossilized fruits were discovered near the village of Mohgaon Kalan in central India, where the remains of the once-widespread volcanic rock lie just beneath the surface in a complex mosaic.