Destructive Duo? Cogon and Talahib at Laguna de Bay in the Philippines

For more posts on cogon grass, click here.

For another post on talahib, click here.

The view from the shoreline of Laguna de Bay in Los Banos, Philippines was fantastic, with the island of Talim rising out of the shallow waters in the distance. But 8 years ago I had just started the first tentative steps in my journey among the grasses, and so when I was taking pictures of the beautiful scenery, I failed to notice two of the dominant plants in that area. 

In the foreground of many of my pictures masses of Cogon grass covered the land, and rising sporadically from the sea of Imperata cylindrica were much taller grasses, their seedheads jutting up like feathery telescopes.

Although sugarcane (Saccharum officinarum) is present in agricultural land in the place, this is probably Saccharum spontaneum, or wild sugarcane, which is called talahib locally.

Spent Talahib flowerheads

I noticed that people tended to mix the two when trying to identify masses of grass, but it's actually fairly easy to separate them.

I. cylindrica is shorter, with blades that seem to come straight up from the ground and fluffy seedheads. The off-center white midrib is also diagnostic, as if the sharp leaf edges when you run your fingers down a leaf. Here is a page that will help identify this species.

Flowering I. cylindrica

These two grasses are the dominant species in grasslands in the country, and Imperata grasslands in particular cover up to 17% of the land area of the Philippines! Like cogongrass, talahib is a staple of the Philippine landscape, and some people even wax lyrical about it. Also like cogongrass, it is heavily used for making various items, such as hats, brooms, baskets, walls and even furniture. In terms of its medical uses, it has been used as an astringent, emollient, refrigerant, diuretic and aphrodisiac.  

Interestingly, the extent of these grasslands has long been blamed on the destruction of forests during the clearing of land for agricultural use, but perhaps there is another story hidden behind what might be a mentality held over from colonial times. However, no matter the truth, such grasslands are very hard to convert to human-usable land due to the difficulty in eliminating the underground rhizomes of cogongrass.

Finally, on a very positive note, both grasses are strong carbon sequesters, with S. spontaneum storing 13.1 t C/ha (87% in above ground shoots), and I. cylindrica accumulating 8.5 t C/ha (only 60% of which is in above ground culms). Another study showed that such Imperata grasslands are net carbon sinks, storing a net of 38.45 g C m–2 year–1 (0.40 Mg C ha–1 year–1). In these days of climate change, you take what you can get.

Closeup of I. cylindrica flowerhead

References

Lales, J.  S., Lasco,  R. D., Geronimo,  I. Q., 2001.  Carbon storage capacity  of agricultural and  grasslands ecosystems in  a geothermal block. The Philippine Agricultural Scientist, 84(1): 8-18.

Karabi Pathak, Arun Jyoti Nath and Ashesh Kumar Das. Imperata grasslands: carbon source or sink? Vol. 108, No. 12 (25 June 2015), pp. 2250-2253