Conservation of imperiled plant species often requires ex situ (offsite) living collections. Protocols for developing these collections most often emphasize sampling depth, but little is known about the genetics of such collections. This study compares how well a single collecting protocol can capture the diversity in wild populations of two closely related species. We selected two exemplar species, bay rush (Zamia lucayana) and sinkhole cycad (Zamia decumbens), based on similarities and differences that allow for rigorous comparison, including geographic isolation and reproductive factors. For each species, we compared in situ plants to ex situ plants via the same panel of 10 microsatellite markers. Genetic distance analysis shows high fidelity of the ex situ collections to their in situ source populations and sub-populations. Structured resampling of allele capture from the in situ populations by the ex situ collections shows that allele capture increases as number of ex situ plants maintained increases, but with a diminishing rate of increase. Difference in the rate of allele capture between the two species was significant at the α = 0.1 level, (p = 0.097) but not at the α = 0.05 level. At larger collection sizes, the difference in rate of allele capture showed a high practical significance (d = 5.41). These data illustrate that a unified collecting protocol can achieve similar allele capture among related species, but also that geographic and reproductive factors can influence the rate of allele capture.

Horticulture is an essential part of plant conservation programs, and botanic gardens are uniquely suited for conservation horticulture work. Here, we present a case study of a successful cycad (Cycadales) propagation program at Montgomery Botanical Center (MBC, Miami, FL), using palma corcho ( Microcycas calocoma ) as an example. This species is highly sought in the nursery trade, and overcollection of wild plants is one factor leading to imperilment of natural populations. Thus, propagation and distribution of palma corcho can make a strategic contribution to in situ conservation. Provenance history of the living collections is reviewed, and techniques for propagation and establishment are detailed. An innovative botanic garden/industry partnership to provide seed for cultivation is discussed. Finally, we present analysis of market forces with regard to rare plant availability and conservation, using palma corcho as an example. Average price per seed has fallen by over half since offered on public auction. This inversely correlates with seed supply, which has been steadily increasing during the last 15 years and helping meet the high market demand. We project the cost of palma corcho will fall further to a point where collection from the wild has no further economic incentive.

Genetic diversity is a critical resource for species’ survival during times of environmental change. Conserving and sustainably managing genetic diversity requires understanding the distribution and amount of genetic diversity (in situ and ex situ) across multiple species. This paper focuses on three emblematic and IUCN Red List threatened oaks (Quercus, Fagaceae), a highly speciose tree genus that contains numerous rare species and poses challenges for ex situ conservation. We compare the genetic diversity of three rare oak species—Quercus georgiana, Q. oglethorpensis, and Q. boyntonii—to common oaks; investigate the correlation of range size, population size, and the abiotic environment with genetic diversity within and among populations in situ; and test how well genetic diversity preserved in botanic gardens correlates with geographic range size. Our main findings are: (1) these three rare species generally have lower genetic diversity than more abundant oaks; (2) in some cases, small population size and geographic range correlate with genetic diversity and differentiation; and (3) genetic diversity currently protected in botanic gardens is inadequately predicted by geographic range size and number of samples preserved, suggesting non-random sampling of populations for conservation collections. Our results highlight that most populations of these three rare oaks have managed to avoid severe genetic erosion, but their small size will likely necessitate genetic management going forward.

Botanic gardens are organized around plant collections, and climate change will affect those collections. Land loss is expected for gardens near sea level, prompting a loss of plants from the collection. Future collection development requires planning for these losses, which in turn requires assessment of the extent and rate of collection loss. We examined collection inventory change over time using records at Montgomery Botanical Center (MBC), to formulate a plant collection half‐life concept. This half‐life was used to project changes inMBC's plant collection over the next 100 years within the context of sea level changes. Comparing predicted rates of collection change with projected rates of loss due to sea level rise, we expect plant collection development to keep pace with climate change. As actively curated resources, botanic garden plant collections can adapt to environmental change faster and more deliberately than natural systems.