# Habitat, seasonal temperature and collection year drive variable germination responses in the endangered plant Harperocallis flava

## TL;DR

This study explores how temperature and habitat affect the germination of an endangered Florida plant, Harperocallis flava, to guide its conservation.

## Contribution

The study identifies specific temperature and habitat factors influencing germination of an endangered plant species.

## Key findings

- Germination of H. flava seeds is highest at winter and late fall/early spring temperatures.
- Germination rates vary significantly across habitats and collection years.
- Summer temperatures reduce germination, suggesting optimal germination occurs when temperatures are below 30°C.

## Abstract

Plant conservation programs strive to integrate information from various life-history stages of focal species when developing holistic recovery strategies. Therefore, in-depth knowledge of the seed-to-seedling transition, a crucial phase that begins with the germination process, provides key perspectives that support recovery. Analyses of seed functions (e.g. germination timing) and related traits (e.g. germination rate, temperature requirements, stress tolerance) in response to selective pressures (e.g. temperature) can fill key knowledge gaps for the seeds of most at-risk plants. Here, we investigated the germination ecology of Harperocallis flava, a rare, globally imperilled, federally and state endangered (government protected) species from Florida, USA. We tested the germination of fresh seeds from three habitats collected over 3 years following exposure to simulated seasonal temperatures of winter (day/night temperatures of 20/10°C), early spring/late fall (25/15°C), early fall/late spring (30/20°C), or summer (35/25°C). We quantified the germination response of H. flava seeds to habitat of origin, seasonal temperature and collection year to determine how these factors influence germination dynamics and to inform seed-based conservation of this and other rare species. Considerable variation in germination responses was observed among the temperature treatments, seed collection years and habitats. Germination tended to be lower at simulated summer temperatures and higher at winter and late fall/early spring temperatures, which suggests that germination in the wild likely occurs in the period following natural shedding while temperatures are below 30°C (i.e. late fall through early spring). Moreover, the spatiotemporal variation of the germination responses highlights the value of basing conservation recommendations on multi-year, multi-population seed biology research when possible.