Words and pictures by Ida Rigby, for Let’s Talk Plants! June 2023.
Palms of the Okavango Delta
Two palms, the real fan palm, Hypnaena petersiana, ...
... and the wild date palm, Phoenix reclinate, ...
... grow in the Okavango Delta. The difference is clear in the photo below of a lion emerging from a thicket of young, bluish leafed real fan palms; behind him are deep green wild date palms.
The real fan palm was named after Professor Wilhelm Peters of Berlin, an early l9th century plant collector who worked in Mozambique. This palm grows in Botswana, northern Namibia and Zimbabwe. It prefers dry, alkaline, sandy soils into which to sink a deep tap root to access the saline water table of flood plains.
It also likes sandy mounds (the golden shrub is a sage) …
… and areas around termite nests.
The wild date palm has a wide distribution throughout Africa and prefers swampy areas and edges of rivers and termite islands (note the African fish eagle on a nest in the dead tree).
It can, however, tolerate periods of drought if there is a high water table. The real fan palm is every safari goer’s delight because male African elephants wander among them in August ...
…shaking the tree trunks to get the palm nuts to fall (note elephant chewed leaf tips on the young palms).
Their ears flap back and forth as they lean into and away from the tree trunk. At night, the sound of a nearby palm being shaken by an elephant, like a soft wind through the fronds, lulls you into a peaceful sleep. Long rows of real fan palms are oft used elephant highways.
Palm nuts that pass through an elephant’s digestive tract germinate more easily, so as elephants poop along their migration routes they leave a trail of palms. The partially digested palm nuts are appealing to baboons, who intently pick through piles of elephant dung searching for morsels of partially digested seeds and palm nuts.
On a walk you can come upon tiny sprouts of the next generation of real fan palms well fertilized by elephant dung.
African elephants chew on the crisp tips of young palm fronds …
… and spit out a fibrous mass of what guides call elephant bubble gum.
Young palms are a favorite target for male hippos marking territory. The hippo backs up to a young fan palm, sends out a blast of poop while spinning its tail, yes, like a fan; the poop hits the “fan” and spreads his unique scent all over the leaves.
One evening I enjoyed the chortling and snorting of hippos plodding about in the marsh outside my tent; the next morning I woke up to a well spattered young fan palm in front of my tent door. Real fan palms are either male or female (dioecious). Male trees have flowers on short spikes; female trees have long panicles of flowers. A mature female tree can produce trusses of 2,000 palm nuts. In addition to elephants, baboons, ...
… bush pigs and fruit bats enjoy the thin layer of ripe fruit on fresh palm nuts. One morning we came upon a herd of male kudus happily chewing on recently fallen palm nuts.
Palm swifts nest under the fronds and use their saliva to make sure that in the wind eggs adhere to the nests. The collared palm thrush also inhabits these palms.
Local people have found many uses for the real fan palm. To make palm wine they cut off the top of the young tree, insert a palm leaf rib as a spout and drain the sap into a container. This ultimately kills the tree. They also enjoy the hearts of palm, but harvesting the hearts is officially discouraged and sometimes outlawed as it kills the tree. Children enjoy the sweet, gingery taste of the thin layer of ripe fruit on freshly fallen palm nuts.
Palm fronds are utilized for thatch, baskets with patterns using natural dyes from roots and leaves …
… hats, fans and mats, and the central ribs are used for kraal fencing and hut construction.
Fibers are used for rope and strings for musical instruments. Pulp is used to treat stomach aches and worms. Ribs and flower stalks serve as fuel for cooking. Palm nuts are called “vegetable-ivory” because the hard, white kernels can be fashioned into buttons and decorative objects to sell to tourists. According to government reports (Environmental Information Service Namibia), in the unprotected areas of Botswana and Namibia, the demand for real fan palm leaves used for crafts for tourists …
… sap for wine, stems for construction and hearts of palm plus the increased browsing by livestock, are dangerously threatening real fan palm populations. On communal lands the survival of this palm is in doubt. In some areas of Botswana there is now conflict between villagers and officials trying to protect the palms.
Another threat to the real fan palm is of course climate change with increasingly long periods of drought and the resultant bush fires. Breeding elephant herds (mothers, aunts, calves and youngsters) enjoy the nutritious leaves of the young palms. Here a mother with her young calf (suckling) and an older sibling are browsing among fresh, young palms.
A few years later, in the same area, fires devastated the palms and a breeding herd that migrated a long distance in search of food, found dramatically different terrain and resources due to the continuing drought. Their long journey was rewarded with dry, burned leaves.
The other palm in the Okavango Delta is the wild date palm, Phoenix reclinata. Phoenix comes from the Greek word for date and reclinata refers to the bent down, arching leaves. It is related to the commercial date palm Phoenix dactylifera. This palm, like the real fan palm, is unisexual. Female trees produce large clusters of small, cream-colored flowers (August through October), which become large sprays of orange fruit (February through April). The dense spiny leaves are a rich green and form dense clumps (the antelopes in the photo are semi-aquatic red lechwe).
Wild date palms like swampy areas …
… and rims of islands and riverbanks; …
… they can also live in seasonally flooded, grassy flood plains so long as the water table is high, and their roots can touch water most of the time.
The passing drama that we were watching across this flood plain was a warthog (above far right) fleeing a cheetah yearling (his mother knew enough not to waste energy on a fruitless chase. Cheetahs depend on surprise and a quick sprint to capture prey). Wild date palms form dense thickets where lion prides rest in the shade for the day, so wandering past these seemingly empty oases can be deadly.
Mouse birds, monkeys, baboons, bushpigs, nyala and bushbuck enjoy the fruit and elephants and baboons like the soft shoots. Birds and animals disperse the date seeds, which germinate easily. An intriguingly named palm-tree nightfighter butterfly caterpillar (Zophoptetes dysmephlia) feasts on the leaves.
Villagers make palm wine from the sap of the wild date palm; children like the gum produced by its roots. Local people enjoy the dates raw and cooked; they also eat hearts of palm, grind palm seeds into flour and roast seeds for a coffee substitute. Medicinal uses include treating urinary tract infections and pleurisy.
Xhosa boys (South Africa and Zimbabwe) wear kilts made of leaf strips for initiation rites. Wild date palm fibers are used for mats, hats, thatch, baskets, rope, bags, sieves, fishnets and fish traps. Its leaves produce a dye. Palm frond ribs are used for roofing, kraals and charcoal. This “wood” resists white ants and fungi and is good for building houses, doors, windows and fence posts. Dried inflorescences are fashioned into brooms. At the end of the day, for visitors, real fan palms along with the baobab are emblematic of the Delta.