Incidence and ecology of very fast germination

Abstract

A group of flowering plant species is known to germinate in less than 24 h from imbibition, but this phenomenon is often overlooked in the current literature. Here, I review this topic by searching the literature published since 1967 and listing the 28 most detailed cases found. Of these, 20 are species of Amaranthaceae (all formerly treated as Chenopodiaceae); 15 of these are from the subfamily Salsoloideae, which is characterized by the possession of spiral embryos. The non-chenopods listed are small numbers of species from the families Acanthaceae, Cruciferae, Gramineae (one species) and Salicaceae (Populus and Salix). Seeds of the Salsoloideae contain fully differentiated embryos. On imbibition, the embryo cells elongate and the spiral embryo uncoils and ruptures the thin seed coat. This can occur in as little as 10 min. Nearly all of the families showing very fast germination have small to very small seeds and little or no endosperm. Most species have soft, thin seed coats that imbibe water readily. All are from high-stress habitats, either arid or saline or from active floodplains, where they can rapidly exploit temporarily favourable conditions for germination. They exhibit one of two contrasting germination behaviours, either having seeds which all germinate within a very short time of wetting or having seed persistence whereby small amounts of rain cause germination of small fractions of seed from a long-living soil seed bank. Serious confusion in the literature in the use of the term ‘opportunistic’ is pointed out and clarified.

Physiological, cellular and molecular aspects of the desiccation tolerance in Anadenanthera colubrina seeds during germination

“…colubrina seeds presented fast germination (nearly 18 hours) and the absence of stage II might be view as an adaptive strategy in colonizing environments. Some authors, as Parsons (2012) report that fast germination species (until 24 h) present thin and permeable integument, which imbibe water promptly, allowing better utilization of temporarily favorable conditions, as is the case of A. colubrina seeds.…”

Effects of dark or of red, blue or white light on germination of subterranean clover seeds

“…A similar pattern of significant differences between the two experiments is found in seeds treated with red light but only in lag of germination. Nevertheless in the two experiments, regardless of light treatment seeds began germinating in less than an estimated 14 hours from the start of imbibition, which qualifies 'Seaton Park' as a very fast germinating cultivar (Parsons, 2012).…”

“…Species with this trait, which evolved independently many times during angiosperm evolution, frequently have small to very small seeds with little or no endosperm or perisperm and thin membranous seed coats that imbibe rapidly (Parsons, 2012;Parsons et al, 2014). However 'Seaton Park' only partially fits in these characteristics.…”

Maternal habitat affects germination requirements of Anabasis setifera, a succulent shrub of the Arabian deserts

“…Parsons (2012) reported 20 species of the family Amaranthaceae that have very fast germination rate. He indicated that the embryo cells of the seeds of these species elongate and the spiral embryo uncoils and ruptures within 10 minutes after imbibition.…”