Lobelia

Undergraduate research at Kent State University in Dr. Andrea Case’s lab, on Lobelia.

Silhouettes (2018–19)

Paper · Download the set (CC BY 4.0)

I restored digitized Lobelia herbarium specimens in Photoshop and turned each plant into a silhouette: 39 silhouettes across 27 species. They form the morphology panel of the phylogeny figure (Fig. 2B) in Godden et al. 2025 (Godden et al., 2025).

For each sheet I unfolded pressed leaves, rejoined broken stems, and removed labels, tape and colour cards, then converted the restored plant to a mask. Nothing was added from other specimens, so a part missing from the sheet is missing from its silhouette. Each file has a 10 cm bar taken from the sheet’s own ruler, which is how the plate above puts every plant on one scale.

Heights are those of the mounted specimen, not the species. A sheet only holds what fits on it: the three L. cardinalis are 24–52 cm, against a published 122–152 cm for the species.

Arnold, J. (2026). Lobelia silhouettes: digitally restored whole-plant outlines from herbarium specimens (2018–2019). Zenodo. 10.5281/zenodo.21764522

The 39 silhouettes, the plate and a table of heights, under CC BY 4.0. The specimen photographs belong to the herbaria that hold them and are not included.

Leaf measurement

Part of NSF award DEB-2015606, which uses Lobelia sect. Lobelia to study why close relatives do or do not grow together.

Leaf shape differs between close relatives and is tied to how a leaf works: light interception, temperature, water supply (Nicotra et al., 2011; Tsukaya, 2018). Many species in the section grow as basal rosettes, which press flat into a pile of overlapping leaves, so the vouchers were taken apart and photographed with the leaves laid out separately. I cropped each leaf in ImageJ, leaving out those too folded or torn to measure, and measured area and perimeter with the LeafArea R package against a 1 cm scale.

In exploratory plots, the perimeter–area relationship looked different between species and between collection sites of L. elongata. This was not tested statistically. The photographs and measurements belong to the Case lab and are not published here.