Scientific Name : Washingtonia robusta H.Wendl.
Common Name : Petticoat Palm, Mexican Fan Palm
Chinese Name : 大絲葵, 華盛頓葵
Family : ARECACEAE
Local distribution status : Exotic species
| Origin | The wild Petticoat Palm is confined to Northwestern Mexico. |
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| Vitality |
Secondary growth is an advanced mechanism characterised by dicots. It allows a plant to grow laterally by lignifying the inner stem and expanding bark tissues towards its periphery. It turns the stem woody and renders the plant stiffness. Unlike dicots, monocots are limited to only primary growth. In easier words, their stems are not hardened. Then, are they relatively fragile? Palms as monocots, however, are vigorous at costal habitats with violent onshore winds. Without secondary growth, how can they acclimatise to such environments? Petticoat Palm, as a model palm species in some studies, helps unravel the mechanisms in behind. The scientists indicated that the bundle cap layer is important to prevent the palm from falling. Before explaining what bundle cap is, we should understand the vascular bundle system in monocots. Plants transport nutrients and water throughout their bodies through vascular bundles. In general, a vascular bundle is a bunch of primary tissues consisting mainly of xylem (water transport) and phloem (nutrient transport). Vascular bundles are abundant and distributed in different patterns between dicots and monocots. By transverse cut through the stems, we can see that the vascular bundles in dicots are arranged uniformly in a ring shape, while they are dispersed in monocots. Usually in palms, the vascular bundles are scattered but rather accumulated towards the periphery of stem. Back to our previous question, what is a bundle cap? Concisely, it is a layer of thick and rigid cells, which is always located at the edge of vascular bundles. This layer is functionally important to support a plant for standing stiffly. In Petticoat Palm, scientists observed that the vascular bundles near the periphery of stem equipped completely lignified bundle cap layers. The vascular bundle could support the stem and render the palm optimal bending under high wind loads. Interestingly, the stiffness of the bundle cap layers gradually decreased towards the centre of stem. They could increase damping and dissipate energy from dynamic wind loads. These meticulous designs of nature can eventually protect the palm from powerful wind strikes. |
| Application | The leaves are always used for building roofs, making baskets and sandals. The fibre is used for making cord. Petticoat Palm is also a wonderful roadside and ornamental palm due to its robust and highlighted trunk. |
| Meaning of names | The generic name Washingtonia is in honour of George Washington (1732-1799), who was the first president of the United States. The specific epithet robusta depicts its robust stem and great adaptability to multiple environments. |
| Growing habit | Solitary palm. |
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| Height | To 27 m. |
| Stem | Stem brownish grey, dead leaves always clustered at the upper stem, with inconspicuous longitudinal striate. Base swollen. |
| Leaves | Fronds palmately divided, splitting into ⅔ of the frond, and tomentose at base, tips drooping. Petioles stout, armed with reddish brown spines. |
| Flowers | Monecious. Spikes axillary, 5-6 branched, pendulous, flowers cream. |
| Fruits | Fruit globular to oval, brownish black at maturity. |
| Flowering period | / |
| Fruiting period | / |
Scientific name above is based on Hong Kong Herbarium website: https://herbarium.gov.hk/en/hk-plant-database/plant-detail/index.html?pType=species&oID=9787
Scientific names from other databases :
― GBIF: Washingtonia robusta H.Wendl.