New to Nature No 81: Spigelia genuflexa

http://www.guardian.co.uk/science/2012/aug/19/new-to-nature-spigelia-genuflexa

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Geocarpy is a term used by botanists to describe the unusual "behaviour" of a plant that deposits diaspores directly into the soil. That is to say, not just its seeds, but also associated tissues that assist in dispersal. Although geocarpy is uncommon among flowering plants in general, it is widespread in at least eight different families. One example known to us all is the peanut, <em>Arachis hypogaea</em>.

Geocarpy is often associated with plants growing in ephemeral or highly variable habitats. It is thought that geocarpy is a means of retaining offspring in a favourable micro-habitat and protecting them from unsuitable conditions, sometimes including fire or predators.

A newly discovered species from north-eastern Bahia in Brazil is the first example of geocarpy in the family <em>Loganiaceae</em>. It belongs to the genus <em>Spigelia</em>, which includes about 60 species of neotropical herbs and shrubs. Members of the genus may be found from about the latitude of Buenos Aires northwards, through Central America and into the Caribbean and southern US. More than half of all species are restricted to South America, with 15 in Bahia alone. And although dwarfism is not unknown in the genus, it is rare and limited to just a few species.The first examples of this spectacular little plant were no more than 3cm tall and were first discovered by plant collector and author José Carlos Mendes Santos. Most were found on exposed roadside soil partly covered by leaf litter, in the Atlantic forest biome.

The flower appears for a short while during the rainy season and disappears completely through the dry season. Other specimens were observed in leaf litter- or moss-covered sandy soil along the border of patches of tabuleiro forest and were taller, up to 25cm.Plants showed two growth forms. The first produces flowers after only three pairs of leaves are formed and the plant is just 1cm tall. The second flowers after four or five pairs of leaves unfurl and the plant is more than 10cm tall. In the first form, the ripe fruit is deposited on the ground; in the higher form, flowers bend but cannot touch the soil.

This unusual and lovely flower was described by an international team of collaborators, led by Alex Popovkin and including co-authors from Western Carolina University, Madrid's Escuela Superior de Ciencias Experimentales y Tecnologia, and Rutgers University. The specific name refers to the "sometimes repeated bending of its infructescence branches to the ground, figuratively evoking an image of the etiquette of genuflection".