Dodder – A Parasitic Plant

On February 9, 2023February 9, 2023 By Bernadette SimpsonIn Plants3 Comments

The Cuscuta genus is the only parasitic genus in the Convolvulaceae, otherwise known as the bindweed or morning glory, family of plants. And Cuscuta species, commonly known as dodders, are the most well-known and widely spread example of stem holoparasitic plants. That’s right, these plants are obligate parasites. They do not contain chlorophyll and cannot, therefore, photosynthesize to make their own food. They must acquire the needed nutrients and water from their host plants.

Folk names, in English, for plants in this genus include wizard’s net, devil’s ringlet, strangleweed, and witch’s hair, to name just a few. I love the imagery of these terms! And once you’ve seen this plant in action, you realize these are great descriptions of these plants that climb, scramble over, and entwine themselves on their host plants with their slender, thread-like stems.

And it is from these many stems that grow haustoria, specialized tube-like growths that insert themselves into the vascular system of the host plants. This allows the dodder to absorb nutrients and water, and therefore grow and attach itself to multiple plants.

“Lab 7 4f) Cuscuta haustoria on host stem xs” by Botanical Voyeur is licensed under CC BY-NC-SA 2.0.

Because the plant does not photosynthesize, there is not much need for leaves, and so the leaves on dodder are very tiny scales. The stems range in color from reddish to yellowish. The small flowers are white, yellow, or cream colored and always hermaphrodites. The stems coil in a counter-clockwise direction.

The parasitic dodder seedlings can germinate and sprout but need to find a host plant quickly, usually within 5 – 10 days, or they will die. They have therefore adapted to use chemosensory, or an ability to sense chemical signals, to grow towards nearby plants. Until they are able to reach a host plant to parasitize, they rely on the food stored in the seed.

Dodder is parasitic on dwarf shrubs, herbs, and grasses and prefers soil with low salinity. We came across dodder in the small oasis of Um Saida (pictured below), near Wadi Kid. The dodder was growing across shrubs of Fagonia sp. as well as herbs such as wild mustard, or jahag (Diplotaxis acris). The dodder was tangled and growing over many plants, clearly illustrating how this could become a problem if the plants parasitize agricultural crops.

There are three species of dodder found in Sinai: Cuscuta palaestina (Palestinian Dodder), C. planiflora (Flat-flowered or Small-Seeded Alfafa Dodder), and C. campestris (Field Dodder). Although Cuscuta species have a rich history of traditional uses in folk medicine around the world, I came across no recorded uses in Sinai in any of the research I was able to access. I am curious to speak with more Bedouin who are familiar with the dodder growing in Sinai.

Camel Spider

On April 25, 2021 By Bernadette SimpsonIn Arthropods3 Comments

Camel spiders, sun spiders, barrel spiders, wind scorpions – all of these common names for Galeodes arabs are misleading as these fascinating critters are neither spiders nor scorpions but rather solpugids, a group of arachnids in the order Solifugae. More appropriately, they are also commonly known as Egyptian Giant Solpugids.

You may have heard of them; camel spiders have been the subject of many urban legends about their size, speed, and appetite. Despite knowing that they posed no threat to me – they are not venomous but can inflict a painful bite – seeing my first one last weekend in Wadi Kid still kind of creeped me out, partly because it was as big as my hand!

Camel spiders can grow up to 15 cm long. They have eight legs, as do most arachnids, plus two large pedipalps, or sensory appendages, in the front that look like legs. (The one I spotted was missing its front right leg.) These pedipalps have a “friction-based adhesive quality” that allows the them to grasp their prey and climb smooth surfaces.¹ Camel spiders have one pair of small eyes on the top of their heads and, with their eight legs, can move quite quickly – up to 16 kph!

These solpugids are voracious predators and eat insects, rodents, lizards, and even small birds. Their favorite prey are grasshoppers though. Camel spiders have two powerful chelicerae, or jaws, that they use to chop or saw their prey into a pulp. They begin by partially severing the neck, using one pair of chelicerae to hold the prey and the other to cut. Alternating the movements quickly between the two pairs of chelicerae, they continue along the whole body. At the same time, they use regurgitated digestive fluids to liquefy the flesh and suck up the nutrients. (And if this doesn’t sound too horrifying to you, visit the first link in the resources given below to read about their mating practices!)

These two distinctive jaws give rise to the name used by the Jebeliya Bedouin for camel spiders – abu hanakain, the father of two mouths.

Solifugae, the order these camel spiders belong to, means those who flee from the sun in Latin. These solpugids often seek shade from the intense desert sun in a person’s shadow and may seem to be “chasing” a person, but really all they want is a break from the heat.

Have you spotted any Egyptian Giant Solpugids during your wanders through South Sinai?

Resources:

1 – Bittel, J. (2017, August 9). Camel Spiders are Fast, Furious, and Horrifically Fascinating. Smithsonian Magazine.

National Geographic – Camel Spider

Aly, D. & Khalil, R. (2011). Wildlife in South Sinai. Cairo. Funded by the E.U. in cooperation with G.O.S.S.

Arghel

On November 13, 2016November 13, 2016 By Bernadette SimpsonIn Plants2 Comments

This is one of my favorite times of year to wander through the wadis of Sinai. For many reasons. Because of recent rains, the wadis are bursting with tiny green baby plants right now. I always enjoy stopping to discover what plants come up first after the rains, and what they look like when they’re so young. Fascinating! For me. 🙂 Another reason I love this time of year is that the arghel plants are in bloom – and they give off such a delightful fragrance!

Some wadis, like Wadi Kid, are lined with arghel plants (Solenostemma arghel), called harjal in Arabic. If you are lucky enough to walk through one of these wadis in November, it will be a joy for your senses! Often you will smell the flowers before you turn a corner and see the plant.

Harjal is an evergreen shrub in the dogbane family. The plants grow up to 1 meter high and 10 meters in diameter. They live in gravelly, sandy, and rocky soils usually at the edge of wadi beds. Here’s a picture of a large harjal plant growing near Wadi Connection in Dahab:

The leaves are greyish-green and their white flowers grow in bunches. The fruits are purplish-green, oval shaped, and can grow up to 5 cm in length.

When they are ripe, they turn yellow and dry to a light brown. They split open, releasing dozens of tufted seeds that are blown by the wind.

Bedouin in Sinai use this plant for medical reasons, as do many people throughout Egypt. Sadly, this plant is endangered due to over-collection for sale at herb shops dealing in medicinal herbs. Locally, the stem and leaves are used to treat a variety of ailments – infected sores and cuts, coughs and colic.

I’m not the only one attracted to these fragrant blooms! Butterflies, bees, and other pollinators are drawn to the flowers’ sweet nectar. In the picture below you can see two orange Painted Lady butterflies – the species I see most often on the harjal flowers – and a Brown-veined White butterfly.