Chasing Madagascar forest grasses: collecting expedition 5 October – 8 November 2011

Maria S. Vorontsova

Can grasses really live in forests? Yes. Forest shade grasses grow in damp areas and have wide leaves to help them capture more light. Millions of years ago forest grasses developed a new system of photosynthesis called C4 and became able to survive in hotter and drier open areas. Their modern descendants in the Forest Shade Clade are particularly diverse in Madagascar and reconstructing their evolutionary history will help us understand how the C4 photosynthesis system arose.

Poecilostachys ground cover in montane rainforest of Marojejy National Park. Many botanists walk through the rainforest looking upwards to search for flowering trees, but there are many interesting things to be found at ground level.

Reconstructing this evolutionary history is part of Russell Hall’s PhD research at the University of Sheffield. Russell planned this trip to collect fresh material for extraction of well preserved DNA. I came along to help identify the species and plan my future work on listing and describing all Madagascar grasses.We were lucky to work with local flora specialists including Franck Rakotonasolo, Mijoro Rakotoarinivo, Hélène Ralimanana, and Tianjanahary Randriamboavonjy from the Kew Madagascar Conservation Centre, Jackie Andriantiana from Parc de Tsimbazaza, and Guillaume Besnard from CNRS Toulouse.

Guillaume is placing specimens into orange desiccating silica gel to preserve the DNA while I am writing up collection notes. In the absence of a table in the wet forest the Kew landrover is very convenient!

Nobody has ever gone searching for forest shade grasses in Madagascar before, and we were anxious about not finding the right plants. We need not have worried: as soon as we entered the wet rainforest we could see nothing but a carpet of Poecilostachys, with broad leaves and long thin inflorescences. As we walked across elevation belts up the Marojejy mountain the shape of the inflorescences changed, and the length of the awns changed, and the leaves became more hairy. So now we have over 30 different collections of Poecilostachys, all similar but with myriads of subtle differences – identification will not be easy!

Dense patch of flowering Oplismenus in a sunny spot in Marojejy National Park. The long thin awns stick to passing animals enabling dispersal.

Oplismenus is the only known grass genus with awns that produce a sticky secretion (awns are the long thread-like structures protruding from grass spikelets). How do the awns produce a secretion? And what is the dispersal mechanism? Nobody seems to know and nobody has ever researched this.

The next best thing after wet rainforest were the rice fields that have not been weeded. Damp areas at the bottoms of valleys and around streams have been converted into rice paddy fields throughout Madagascar, and as our car went around the bends in the road we had to keep our eyes peeled for untidy rice paddies with weeds. When the earth barriers separating the individual rice paddies are built or repaired Alloteropsis seeds in the soil germinate: the young Alloteropsis seedlings love water and are visually almost indistinguishable from rice plants. They go on to produce a dark tall panicles where the upper flower in each spikelet grows a long awn.

Plant collecting in the dark: Guillaume is using a torch to identify a species of forest Panicum while Russell is pressing Poecilostachys.

After five weeks in the field and 250 grass collections we feel confident that we have advanced the overall state of knowledge of grass diversity in Madagascar as well as finding material for DNA extraction. For future outcomes from this research see the University of Sheffield Evolutionary and Environmental Physiology laboratory website.

One of the few remaining intact plants of Dioscorea strydomiana in habitat.

Paul Wilkin visited South Africa October 5-13 as part of a collaborative project with Dr. Muthama Muasya (UCT) and John & Sandie Burrows (Buffelskloof Herbarium).

The visit had two main aims. Firstly, collections were made for UCT geared towards a revised taxonomy and a species-level phylogeny of the predominantly South African perennial-tubered clade of Dioscorea. The visit was also geared towards providing a scientific basis for conservation of  the critically endangered D.strydomiana. The locality of that species was visited with staff of the Mpumalanga Tourism and Parks Agency. It was agreed that a conservation action plan and funding for it is urgently needed to prevent extinction. This charismatic but slow-growing and dioecious yam is known only from ca 200 individuals. The above ground tubers of plant which unusually has this non-twining stems are being heavily harvested for medicinal use.

The remains of a tuber base following heavy harvesting, resuting in exposure of the tuber parenchyma to water and subsequent rotting and plant death

An extensively harvested plant with four new shoots at the tuber margin

In addition to the Dioscorea work, the eMonocot workshops in 2012  were also publicised and plants from 16 of the 78 monocot families were seen in just 4 days in the field. They included unusual taxa such as Behnia reticulata (Asparagaceae) and Prionium serratum (Thurniaceae). These two genera are endemic to the region. Other highly attractive monocots encountered included Disa woodii (Orchidaceae), Scadoxus puniceus Watsonia confusa (Iridaceae). These plants highlight the major contribution of South Africa to monocot plant diversity worldwide.

Watsonia confusa, endemic to the Eastern Cape and KwaZulu Natal

Scadoxus puniceus or paintbrush lily

Disa woodii, an endemic terrestrial orchid.

During a recent field trip to the Caribbean island of
Montserrat, myself and Marcelo Sellaro discovered plant species which had not
previously been known to occur on the island. I specialise in the Araceae
family (Aroids), while Marcelo looks after the Aroid and Bromeliad collection
in Kew’s Horticulture department. Read more about the beautiful island of
Montserrat and the interesting monocots we found there on the Kew UK Overseas Territories
blog.

Participants of the BioSynC 2011 meeting, The Field Museum, Chicago, 26th to 30th September 2011- Photo credits: BioSynC Carex group

Dave Simpson (4th from right, middle row, Kew), Odile Weber (5th from left, front row, Kew) and Ed Baker (1st on left, front row, NHM) have been in Chicago this week for the BioSynC 2011 meeting, where they're presenting and giving workshops on the eMonocot Cyperaceae scratchpad.

For more news on how the meeting has progressed follow this link: http://systematics.mortonarb.org/carex/index.php/Overview_of_eMonocot_an...

Look out for Odile's blog when she returns to the UK.