Depth, mass and palatability of geophyte underground storage organs of the Cape Floristic Region

Description

The dataset spans 1,828 individual plant underground storage organs (USOs) sampled from diverse vegetation types across the coastal forelands of the Cape Floristic Region of South Africa. The data include USOs from 153 species, 54 genera, and 22 families. The depth of burial and wet mass of each USO were recorded, and USOs were categorised by growth form type and palatability to human foragers (details below). Of the sampled USOs, 363 were bulbs, 955 were corms, 213 were rhizomes, and 297 were tubers, while 1588 were palatable and 240 unpalatable.

Steps to reproduce

Plant USOs were sampled across the coastal forelands of the Cape Floristic Region (South Africa) in various vegetation types (Sandstone Fynbos, Sand Fynbos, Renosterveld, Limestone Fynbos, Limestone Strandveld, Dune Strandveld, Subtropical Thicket, and Forest) during the austral autumn and spring of 2011 and 2015–2017. Sampling was done in a total of 450 plots of 5 x 5 m2, with a hundred plots sampled in spring (as this is the time of maximum apparency of geophytes; Singels 2021) and fifty plots in autumn in each of the three coastal regions (west, south, and southeast). For each species in flower, the first 10-15 plants encountered were excavated and USO depth measured as the distance (in mm) from the soil surface down to the top of the USO (hereafter ‘depth’). We chose depth to the top rather than to the lowest part of USOs as the former is most relevant to humans and other mammals that dig down from the soil surface. Additionally, the biomass (wet mass) of each USO was recorded. Although wet mass may vary seasonally, the moisture content of USOs also has relevance for their palatability and thus the size of the reward offered to predators (Singels 2021). Sampled USOs were classified into four main types, namely bulbs, corms, rhizomes, and tubers (sensu Tribble et al. 2021). We also used the categorisation of edibility derived by Singels et al. (in press A) based on energy-, nutrient-, moisture-, fibre- and tannin contents, to classify the palatability of USOs to humans, whereby Singels et al.’s ‘edible’ USOs were classed in this dataset as palatable, and ‘unpalatable’ and ‘poisonous’ (after Singels 2021) USOs classed here as unpalatable. References: Singels, E., 2021. The role of geophytes in Stone Age hunter-gatherer subsistence and human evolution in the Greater Cape Floristic Region. PhD thesis, Department of Archaeology, Faculty of Science, University of Cape Town, Cape Town, 312 pp. Singels, E., Grobler, B.A., Parkington, J., Esler, K.J., Cowling, R.M., in press A. Spoiled for choice: the remarkable diversity of underground storage organs with high energetic returns available to Stone Age foragers in the Cape Floristic Region, South Africa. Current Anthropology. Tribble, C.M., Martínez‐Gómez, J., Howard, C.C., Males, J., Sosa, V., Sessa, E.B., Cellinese, N., Specht, C.D., 2021. Get the shovel: morphological and evolutionary complexities of belowground organs in geophytes. American Journal of Botany 108(3), 372-387.

Institutions

• University of Cape Town
• Stellenbosch University
• Nelson Mandela University

Categories

Funders

• National Research Foundation

  Singapore

  Grant ID: CPRR14072880885 & NSTA250121297797 (NRF of South Africa)
• Palaeontological Scientific Trust

  South Africa

Licence