Reprinted from the UCI Arboretum 'Arboretum Quarterly' Vol. 3 No. 2
There are thirty-three currently recognized species in the genus Gethyllis. Most are found in the Cape Floristic Region with a few species widely distributed throughout southern Africa and Namibia. Gethyllis grow in areas with little rain that falls mainly in the winter. It is a curious plant that is always popular at our Spring Open House, when the foliage is present. The Arboretum is lucky to house approximately half of the Gethyllis species.
Unlike most plants that flower and leaf at the same time, Gethyllis has three separately occurring phases in its yearly cycle - leafing, flowering, and fruiting. The fruiting and leafing phases can occasionally overlap.
As with most plants the foliage grows while a sufficient supply of water is present. In the Cape this happens to be in the cool winter. The leaves are generally light grey-green in color and linear in shape. Many of the species have gently twisted leaves which spiral out of the sheathed neck of the bulb giving the plant an exotic, striking appearance. Some species even have hairs covering the leaves. These adaptive traits, which make the plants so popular, are thought to help protect the plant form the sun and reduce their water loss from evaporation. As the rainy season comes to and end and the temperatures rise, the foliage dies back to the sheathed neck and the bulbs begin to go dormant.
Once it is hot and dry, the bulbs enter their flowering phase. Due to the large amount of energy it takes, each bulb can only produce a single short lived flower in any one year. The sheathing neck left over from the dried leaves helps protect the delicate white or pink flower from the hot sun baked soil. With the flowers lasting only a few days, it is essential that as many of the plants as possible bloom at the same time if they are going to be pollinated. Since most of the plants tend to bloom within a day or two of passing cold fronts, their bloom is thought to be regulated by atmospheric pressure. With greater decreases in barometric pressure, more and more plants bloom simultaneously resulting in both a more spectacular bloom and more importantly increasing the likelihood that each plant will be pollinated.
Once pollinated, the third and final phase, fruiting, begins. It can take more than two months to produce the club shaped, aromatic fruit which ripens just in time to release the seeds for the rainy season. The seeds have an extremely short viability and will only last until the rainy season begins. This interesting reproductive strategy occurs in a variety of plants that grow in arid environments. It enables the plant to grow a longer time that first season which helps it build a sufficient store of energy to survive the hot dry dormant period. This adaptation may give the plant a better chance of survival in the wild, but the seed's short viability is the bane to many a conservationist making gene banking very unlikely.
The very adaptations that enable these fascinating plants to survive in such a harsh environment, also make it difficult to maintain them in conservation collections. They require soils with excellent drainage and can be difficult to grow for those who like to water generously. They are poor vegetative producers but seed readily when cross pollinated, however a sufficiently large population is needed to ensure good seed sed. Lastly, due to their short seed viability, they can not be gene banked. Those that have seen these intriguing plants are sure to agree that they are worth the trouble.
References:
T.H. Arnold and B.C. de Wet (eds.) 1993. Plants of southern Africa: names and distribution. 825 pp. National botanical institute. Pretoria.
Neil Du Plessis and Graham Duncan, 1989. Bulbous Plants of Southern Africa: a guide to their cultivation and propagation. 192 pp. Tafelberg Publ. Ltd. Cape Town.