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Short Notes on Nature Singapore

25 June 2017 | Florida Hammock Sandmat | Euphorbia ophthalmica |

Following the addition of a new plant to my website last week, I found another new plant recently. It was not in some kind of forest where the chance of finding something new was higher, but in the park next door. It was a small spreading weedy plant that looked like a miniature version of the Asthma Weed (Euphorbia hirta). It took me around 2 weeks to nail down an identity which I think was reasonably correct --- Florida Hammock Sandmat (Euphorbia ophthalmica). As far as its common name is concern, it is probably very common in Florida in USA. The overall appearance with its slightly erected branches might look like a hammock depending on one's imagination. The sandmat part is likely due to its habitat which may be in sandy area and its tendency to form a mat-like spread. That is how I interpret its common name since I was not able to find another of its common name.

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So far, this was the only population of this herb seen. They were hidden in clefts formed by large rocks by the side of the cemented path. The rock and the plant's small size had probably protected it from being shaved by the regular grass-trimming activities in the park. The plant likely landed on our shore quite recently as it was not reported in any flora listing in Singapore. The source was relatively easy to guess. I highly suspect that its seeds travel with the plants or soil imported from overseas.

Based on the PIER website, the closest location to us where this plant was naturalized was Australia where it was first reported there in 2001 [1]. The report used the botanical name Chamaesyce ophthalmica which is a synonym of Euphorbia ophthalmica. Euphorbia ophthalmica was once considered a variant of Euphorbia hirta (Euphorbia hirta var. procumbens) [2].

Due to the discovery of this plant, I had renamed all the Chamaesyce species in my website to Euphorbia species and treat Chamaesyce as a synonym of Euphorbia. Some botanists in the past had recognized Chamaesyce as a standalone genus [3]. More recently, Chamaesyce was treated as part of Euphorbia, usually as a section.

I will be on the lookout for more of these imported species in parks.

References:

[1] Harris WK. Chamaesyce ophthalmica (Pers.) Burch (Euphorbiaceae): a weed species newly recorded from Australia. Plant Protection Quarterly 2001;16(1):31-32. | Abstract |

[2] Steinmann VW. Euphorbia nocens, formerly a variety of Euphorbia hirta (Euphorbiaceae). Acta Botanica Mexicana 2003;64:37-44. | Read article |

[3] Yang Y, Berry PE. Phylogenetics of the Chamaesyce clade (Euphorbia, Euphorbiaceae): Reticulate evolution and long-distance dispersal in a prominent C4 lineage. Am J Botany 2011;98(9):1486-1503. | Read article |

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