Next-generation digitization: integrating spectral reflectance into the online mobilization of herbaria

What this was about

Matthew Austin described how Missouri Botanical Garden, with philanthropic support to digitise its roughly eight million herbarium specimens, is adding spectral reflectance as a 'third layer' of digitisation alongside images and transcribed labels. After imaging and barcoding, a spectral team takes three point measurements per leaf surface on selected specimens (leaves liftable onto a black background, free of glue or pathogens, woody taxa with in-house curatorial expertise), recording rich per-scan metadata under the protocol of iHerbSpec, a 30+ institution working group. Data are linked in Tropicos by barcode; about 1.55 million specimens have been imaged and 16,000 have spectra, and clade-specific species identification models trained on expert-identified spectra achieve accuracies around the 90s, even identifying sterile specimens.

Why it matters. Extends the digital extended specimen with chemistry/phenotype data and shows a standardised cross-institution protocol for making it reusable.

In the room

• Spectral reflectance encodes chemical and physical properties and can infer functional traits and aid identification.
• The project also funds a curatorial mentorship programme pairing 18 digitisation staff with curators.
• Transcription is outsourced to MAX Communications with in-house QA before upload to Tropicos.
• Measurements are point spectroscopy (three per leaf surface), not full-specimen imaging.
• Metadata include leaf surface, developmental stage, perceived preservation and contamination.
• iHerbSpec developed the first standardised protocol for herbarium spectral measurements, with file naming and metadata conventions; it meets annually in person and monthly online.
• Spectral files link to specimens by barcode with a Tropicos UI to fix unmatched files.

Notable moments