Observation Series
Horse Drunk Grass (Hippobroma longiflora)

The Chinese name of this plant is "ma zui cao" (马醉草), literally translated as "horse drunk grass" while its botanical name is Hippobroma longiflora, which literally means Horse Madness Long Flower. According to unknown legend, horse feeding on this herb showed signs of drunkenness or madness speculated to be caused by the chemical contents in the plant. The common names in English are Star of Bethlehem, Madam Fate and Star Flower. Although this is not a native plant in the Asia region but the Caribbean Islands, it had been naturalised in many countries including Singapore. It is sold in plant nursery as well, which was how it got naturalised at my balcony area. I got the pot of plant back in March 2011.

photo photo photo The first time that I saw a live specimen of this herb was in Malaysia in 2007 while the first sighting in the wild in Singapore was in 2012 in Mandai area. This was when I knew that it was not a rare herb here but confined to certain open areas with ample supply of sunlight. The herb proliferated very well in my balcony area Within 2 years, photo photo it had expanded on its own to a few other pots. The rapid spread of the plant was due to its huge quantity of tiny dark brown seeds that got released from its matured fruits into the surrounding soil. I suspected that the ants might have help with carrying the seeds around in addition to me recycling the soil for other plants.

Since I had a many of this herb growing all over my pots, I thought of doing a more in depth exploration on its structures in May 2013. The main advice that you will notice in the Internet on handling of this herb was its poisonous milky sap that leaked out when the plant was injured. After slicing through the stem and leaf, there was indeed milky sap flowing out. However, the quantity was low, at least not those dripping or spurting types. Many plants have milky sap and I do believe they are toxic too. It was mentioned in several online websites that the sap may cause blindness when it get into the eyes. In general, it is not wise to get any foreign materials into the eyes and this sap should be no exception.

Some websites (e.g. Wikipedia and Asian Plant site) mentioned that the sap or plant "is notable for its concentrations of two pyridine alkaloids: lobeline and nicotine". However, there was no reference to a publication where such information was obtained. After some search, I could only land on a 2009 article that indicated lobeline was available in this herb. It was more likely that the drug, lobeline found in this herb affect the nicotine receptor in the body or lobeline has a similar effect as nicotine. It might not be true that this herb contains nicotine.

There was a good reason for the fruit (capsule) to hang in a drooping position on the stem. After I finally get to know how the seeds were released, seed collection from this plant became a fun activity. To harvest the seeds, pick the slightly dried up capsule with the dried tubular flower still attached; hold the capsule with the dried flower end facing skyward to avoid the seeds from dropping out prematurely; remove the dried flower and the sepals to expose the small openings at the end of the capsule; turn the capsule with the opening end pointing downward and gently tap on the side of the capsule. Stream of tiny dark brown seeds should fell out from the capsule. To have a contrasting effect, it is better to place a white paper below to collect the seeds. A capsule is likely to contain more than a hundred seeds.

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It is clearer to view the internal structure of a capsule from an unripe one instead of a ripe one. In the ripe or almost dried capsule, the compartments within it are already shrunk which make it difficult to visualise the structure. Each capsule has 2 compartments that housed numerous whitish yellow unripe seeds which was clearly illustrated in the cross-sectional cut picture. The longitudinal cut along the length of the capsule offered the clue on how the seeds are being released at the tip of the capsule. In the picture on the far left, the greenish fibre-like structures are the sepals.

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photo The plant has a taproot system with extensive network of fine secondary roots that penetrate deep into the soil. The overall appearance looked like ginseng roots. Before the old plant dies, young plants would emerge from the same spot where the old plant resides. The most distinctive feature of the plant is its long-tube white flower that has a length of about 11 centimetres. Flowers are likely self-pollinated since every flower produced a capsule with numerous seeds.

The milky sap is not visible in the unripe capsules. It is concentrated in its stem and the major vein of the leaves. Regarding the poisonous status of this plant, some statement might be an overkill. For example, the book titled "Poisonous Plants of Paradise: First Aid and Medical Treatment of Injuries from Hawaii's Plants" published in the year 2000 mentioned that "touching this plant can cause redness and a painful pins-and-needles sensation" (page 154). From my experience, this was untrue at all. I had been using my bare hands to prune the plant and did not experience such sensation. Nevertheless, I am quite sure that the sap is toxic to the eyes or any open wounds.

Without the flowers, this herb looks quite similar to another plant, the Sawtooth Coriander (Eryngium foetidum). This is especially so for their young plants.

Online References: | Urban Forest | Plants of Southeast Asia | Flora of China | Pacific Island Ecosystems at Risk (PIER) | Flowers of India |

Last updated: 24 July 2016

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