Leaf Morphology: Arrangement

On September 26, 2021 By Bernadette SimpsonIn PlantsLeave a comment

Since my guidebook was intended for nature-lovers, not necessarily plant specialists, I took care to define and explain the technical terms used in the descriptions of the plants in my book, choosing simpler English synonyms when possible. But it’s not always possible. So I thought it might be helpful to dedicate a few blog posts to delving into some of these technical terms a bit more, deepening our understanding and looking at some specific examples from our desert plants. And I thought I’d start with the terms used in leaf morphology.

In botany, morphology is the study of the size, shape, and structure of plants. Plant biologists use these characteristics for the descriptions, classification, and identification of plants. Having some understanding of these different characteristics will help you to recognize and identify the plants you see while wandering through wadis.

In leaf morphology, one of the key characters studied is leaf arrangement, the number and placement of leaves along the stems. This arrangement of leaves is called phyllotaxy and we’ll talk today about four general categories – alternate, opposite, whorled, and rosette – although there are various levels and ways of categorizing these patterns.

A node is the point where the leaf emerges from a stem or twig, and arrangement is always regular.

In the alternate pattern, sometimes called spiral, each leaf or leaflet grows from a different node.

In the opposite arrangement, two leaves or leaflets grow per node, on opposite sides of the stem.

If, in this opposite pattern, the successive leaf pairs grow at right angles, it is called decussate. These perpendicular pairs of leaves are typical of plants in the mint (Lamiaceae) family, like the ones pictured below.

In the whorled arrangement, three or more leaves or leaflets are connected at one node. Blepharis attentuata, pictured below, grows whorls of four leaves.

When the leaves of the plant emerge from the base in a whorled arrangement, spreading out in a circle, it is called a rosette.

Understanding the various patterns of leaf arrangement will help you to understand plant descriptions that you read in my book and other sources. And if you come across a plant you do not know, take note of its leaf arrangement (Photos are a great way to document this.) because it could be an important characteristic to consider when identifying the plant. In the next few posts, we’ll learn about other key characters in leaf morphology that will help us identify the plants.

One of my favorite desert plants is the caper bush; its leaves grow in an alternate pattern. I also love germander (Teucrium sp), both for its delicious fragrance and its neat geometrical leaf pattern. Do you recognize these leaf patterns in any of your favorite desert plants?

Darkling Beetles

On September 17, 2021 By Bernadette SimpsonIn ArthropodsLeave a comment

Even if you spot no other critter while wandering through wadis, you are almost guaranteed to see at least one darkling beetle, likely scurrying across the sand to find safety under a desert plant.

Darkling beetles are what we commonly call the beetles that make up the Tenebrionidae family of beetles (Order Coleoptera). There are more than 20,000 species of darkling beetles worldwide. In Egypt, there are about 400 different species, around 120 of those can be found in Sinai. I believe most of the darkling beetles that I have photographed belong to the Adesmia genus, but I have not been able to narrow down the identification any further.

Though most darkling beetles are dark in color, they are actually named for their nocturnal habits. A few beetles are colored or patterned, sometimes with red. Many of the larger species, like the ones pictured here, are flightless. The elytra (the rigid, forewings) are fused.

The domed shape of these darkling beetles, particularly those in the Adesmia genus, remind the Jebeliya Bedouin of donkeys. They refer to them as ‘uwir al banat, or “newborn donkey for girls”. ¹

Darkling beetles are common in desert areas, where they fill an ecological niche as plant scavengers. They are generalist omnivores though, meaning they can feed on a wide variety of plants and animals. As both larvae and adults, they feed on fresh or decaying plant matter like leaves or rotting wood. They will also eat fungi, dead insects and larvae. You will find darkling beetles living under logs and stones, in termite and ant nests, in plant debris, and in the dry dung of animals.

I always enjoy coming across these beetles while I’m wandering. They are entertaining to watch as they scuttle out of the way or over rocks. They are a good reminder that I am not alone out there, that there is a variety of wildlife surviving in our desert wadis.

On a lunch break in Wadi Lebba a few years ago, a darkling beetle was brave enough to approach our picnic spot so I shared a bite of orange with him.

If you’ve not spotted a darkling beetle on your wanders yet, watch the ground a few meters in front of you on your next hike. Or stop for a break near some plants. If you’re quiet, you might even hear them scrambling around.

References:

1- Zalat, S., & Gilbert, F. (2008). Gardens of a Sacred Landscape: Bedouin Heritage and Natural History in the High Mountains of Sinai. Cairo: The American University in Cairo Press.

Blackstart

On May 20, 2021 By Bernadette SimpsonIn Birds2 Comments

It’s been awhile since I’ve featured a bird on the blog, so today let’s meet the Blackstart (Oenanthe melanura), called bal’ala by the Jebeliya Bedouin.

Blackstarts are common resident birds in South Sinai and are relatively unafraid of humans so there’s a good chance you’ll come across one in your wanders and maybe even get a chance to spend some time in their company. You might be serenaded by their song:

David Marques, XC82635. Accessible at http://www.xeno-canto.org/82635

These birds have bluish-grey to grey-brown plumage with darker colored wings. They are named (Oenanthe melanura) for their black tails, which they tend to have fanned out. In classical Greek, mela means black and oura, tail. Their bodies can be up to 14 cm long.

Blackstarts live in rocky wadis, deserts, and mountain slopes, where they can often be seen hopping around on the ground, feeding on insects.

Blackstarts are monogamous and pairs remain together in their breeding territory throughout the year. The female builds the nest, a shallow cup made of grass and leaves, in rock crevices and lines it with hair and fine plant material. She will lay 3 – 4 eggs, which are blue with reddish brown speckles. The eggs, if they aren’t preyed upon by a Golden Spiny Mouse, hatch after about 13 days. Both parents feed the chicks, which fledge, or grow flight feathers and are ready to learn to fly, after 14 days.

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.

Sand Wasp

On April 15, 2021 By Bernadette SimpsonIn ArthropodsLeave a comment

It’s springtime and the air is full of the sweet scent of flowers and the sound of buzzing insects. Some of the buzzers I’ve spotted recently in my garden are strikingly-colored sand wasps (Bembix sp.).

Sand wasps are solitary hunting wasps that build their nests in the ground. Worldwide, there are over 350 different species in the Bembix genus. They are typically yellow and black and are reported to be particularly diverse in dry habitats. Bedouin in Sinai call all wasps dabra.

Adult sand wasps feed on nectar, but the females are skilled hunters, capturing prey to feed their larvae. The females dig nests in the ground using their mandibles and front legs. The nests are simple burrows with an enlarged chamber at the bottom, the brood cell, which they keep stocked with fresh prey for their developing larvae. It is not uncommon for several females to dig their nests in a common area, but they are not social; they do not cooperate or share the labor.

Flies are the most common type of prey hunted, but sand wasps have also been observed preying on damselflies, grasshoppers, mantids, bugs, antlions, lacewings, butterflies, bees and wasps – but not beetles or spiders. The adult sand wasps catch the prey in mid-air, paralyze them with venom, and then carry them back to the waiting larvae.

After they have had their fill, the larvae spin silk cocoons and enter a prepupal stage. Pupation may not occur until the following spring, and then male wasps will emerge before female ones. Adult sand wasps probably live from several weeks to several months and spend much of their time sleeping. They spend this inactive time within their nests or in temporary sleeping burrows. The adult sand wasps may be prey themselves – to birds, lizards, robber flies, antlions, and velvet ants.

One source I consulted reports that these solitary wasps do not attack and sting humans, but another says they can deliver a painful sting if their nest is disturbed. So, like all stinging insects, it is best just to leave them in peace.

Have you spotted sand wasps on your wadi wanders or in your garden?

Resources:

Evans, H. & O’Neill, K. (2007). The Sand Wasps: Natural History and Behavior. Cambridge: Harvard University Press.

Scarce Marsh Helleborine

On March 23, 2021March 24, 2021 By Bernadette SimpsonIn PlantsLeave a comment

If you follow the Wandering through Wadis Facebook page, you might recall the photographs of orchids that I shared a few weeks ago. I had no idea that there were orchids growing in the desert, but after my friend sent me photos of the blooms she had seen, I obviously had no choice but to go see them for myself.

I had identified the orchids in my friend’s photos as Scarce (or Eastern) Marsh Helliborine (Epipactis veratrifolia) but, admittedly, I knew nothing about orchids. So I’ve been reading up on them. And I’ve learned a lot of fascinating things about orchids in general, but also about these rare beauties that are native to Sinai. (They are not found in mainland Egypt.)

Most orchids (more than 99% of all species) are epiphytic and use their roots to attach themselves to and grow on trees. The Scarce Marsh Helleborine, however, is a terrestrial, or ground, orchid and grows its roots firmly in soil.

This helleborine is a perennial herb and grows, from a fleshy rhizome, to be between 25 – 150 cm tall. The leaves are ovate (egg-shaped) and pointed at both ends. They grow along the stem and can be 8 – 25 cm long. The inflorescence, or cluster of flowers, grows atop an erect stem. The flowers are fairly open and are green to yellowish-green in color with purplish or reddish radial stripes. The lip, or bottom middle petal, is tipped in white. The upper part of the stems, bracts, ovaries, and sepals are covered in short, fine hairs. In Dahab, the orchids were found growing among native grasses in a wet area.

Like all orchids, this helleborine is dependent on a mycorrhizal symbiosis, a mutually beneficial relationship between a plant and a fungus, to complete its life cycle. The plant’s fruit capsule is full of microscopic seeds (in some species, over a million), but these seeds all lack endosperm. Endosperm is the tissue usually found inside seeds that provides nutrition to the plant as it sprouts. Because an orchid’s seeds don’t have this inborn nutrition, they rely on fungi to provide them with the nutrients they need to germinate. The chance of germination is so small that only a minute fraction of the released seeds grow into adult plants.

But before a plant can even produce any of these seeds, it must first be pollinated. And to help ensure that, the Scarce Marsh Helleborine employs a trick, a special mimicry, to lure pollinating hoverflies to its flowers. The flowers emit three chemical substances that are usually released as alarm pheromones among aphids. Aphids are the preferred diet of hoverfly larvae. So female hoverflies smell these chemicals, interpret this to mean that aphids are nearby, and proceed to lay their eggs near the source of the scent – the flowers. The hoverflies are rewarded with a small sip of nectar, but their larvae are doomed to starve because, when they hatch, there will be no aphids around to consume. (This is a strange contradiction from an evolutionary perspective because since the larvae die, the number of potential pollinators decreases.) The orchids are mimicking the aphids, taking advantage of the female hoverflies and deceiving them into pollinating the flowers.

As you can see, these rare orchid blooms are not only beautiful but also full of amazing natural wonder!

Resources:

Plants of the World Online (Epipactis veratrifolia)

Orchid tricks hoverflies (Max Planck Society)

The Third Edition is Here!

On March 18, 2021March 23, 2021 By Bernadette SimpsonIn UncategorizedLeave a comment

I’ve had many requests over the last couple of years for print copies of the guidebook. I decided that if I was going to print more, the book should be the best, most up-to-date version possible. So that’s what I’ve been working on, updating the book. It’s been four years since the printing of the second edition, and eight years since the first. I continue to discover and learn about the desert plants and so, to this third edition of the book, I have added 13 new plants (for a total of 155) and 90 new or additional photographs for the plants previously included.

And now I finally have a limited number of print copies available of the third edition of Wandering through Wadis: A nature-lover’s guide to the flora of South Sinai!!

The book is printed on thick quality paper bound with spiral wire 2 cm round. The book is 21 cm x 14.5 cm, about A5 paper size. It weighs 518 grams. Something to consider when deciding if you would want to carry it with you on hikes.

A bonus to reading the eBook version, especially on a tablet, is that you can easily zoom in on the photographs of the plants.

Also, depending on your device, it may weigh less than the print copy. My tablet, in a case, weighs 400 grams (100 less than the print copy).

One useful feature of the PDF version, especially when read on a laptop or PC, are the bookmarks that help you easily navigate through the book.

You can download a sample of the book as a PDF file for free here . This requires an email address. If you’d rather not enter an address, click the ‘Preview’ button on the top of this page to view the file online.

Print copies cost LE 400, including free delivery in Dahab. Shipping is possible within Egypt. Send me a message to arrange purchase and delivery of your copy.

The eBook version has also been updated and can be purchased online for $8 here. Contact me if you would like to arrange alternative payment and delivery options. Enter code WADIBLOG for a 10% discount.

Happy Wandering!

~Bernadette

Desert Plant Adaptations (IV) ~ Leaf Adaptations

On February 20, 2021 By Bernadette SimpsonIn PlantsLeave a comment

Getting back to my series on desert plant adaptations, let’s discuss some of the ways that leaves have adapted to help plants survive the hot and dry conditions of the desert wadis.

Besides dropping all of their leaves like drought-deciduous plants, some plants simply have smaller or fewer leaves. Smaller leaves means there is less surface area open to the wind and sun, and so less water is lost through transpiration. Semi-shrubs and shrubs may have large leaves in the winter that are shed during the dry season and are replaced with smaller leaves in the summer. Artemisia herba-alba and Phlomis aurea both have smaller summer leaves.

Another strategy that helps conserve water is folding or rolling up the leaves so that the stomata are facing inwards, reducing the surface area subject to transpiration. This adaptation is employed by Helianthemum species, Fumana thymifolia, and many perennial grasses.

But it’s not just transpiration that leads to water loss. Leaves also lose water through their cell walls. To combat this, the leaves of some desert plants have a waxy coating or a thick cuticle, the film covering the surface, which helps seal in and protect moisture already in the leaves. Most xerophytes have a thick cuticle.

Hair on the leaves and stems also helps reduce water loss by providing shade and trapping water vapor near the plant’s surface. Artemisia herba-alba, Phlomis spp., Majorana syriaca, and other plants utilize this adaptation.

Plants needs energy from the sun to photosynthesize. What energy they don’t use to make food is used to heat the leaf up. That is very useful for plants growing in cold climates whose leaves need to be a bit warmer to photosynthesize but not so necessary for desert plants, which must reflect some of this solar radiation or risk over-heating. How do they do this? Some plants, like Capparis sinaica, have a waxy coating on their summer leaves which gives them a lighter – and more reflective – color than their winter leaves.

Leaves of Atriplex species also have a different color depending on the season, but they don’t use a waxy coat. Instead, the leaves are covered in vesicular hairs that contain a salty solution. In the winter, the hairs are full and transparent, allowing more absorption of the sun’s energy. In the summer, the water evaporates and the hairs dry out causing the leaves to be a lighter color that reflects the sun’s rays.

You can read more about each of the species photographed above in my book. In the next post in this series, we’ll learn about stem adaptations. Stay tuned!

Pantropical Jumping Spider

On January 25, 2021 By Bernadette SimpsonIn ArthropodsLeave a comment

Over the past several years, I have really come to enjoy watching the jumping spiders in my garden and, of course, while wandering through wadis. The Pantropical Jumping Spider (Plexippus paykulli) is one of the more common – and dramatically-colored – ones that I can see close to home.

I was not surprised, then, to learn that this species is often associated with buildings and man-made structures and may be found near light sources.

Both sexes of this species have a high carapace (upper section of the cephalothorax, the front part of the body where the legs are attached) and are covered in short grayish hairs.

Males, pictured above, have a black carapace and abdomen with a broad white stripe running through the center. There are also broad white stripes along the sides and a pair of white spots towards the rear end of the abdomen. The face appears to have three white stripes, which you can see clearly in the close-up photo below.

Immature spiders, as well as females like the one pictured below, are brownish-gray in color with a broad tan stripe through the center of the carapace and abdomen. Towards the end of the abdomen, the stripe breaks into chevrons, v-shaped marks.

*“Plexippus paykulli f. 8mm PA183907” by Pen Araneae is licensed under CC BY-NC-ND 2.0*

Like all jumping spiders in the family Salticidae, Pantropical Jumping Spiders have incredibly acute eyesight. They have four pairs of eyes, with the middle pair in the front quite a bit larger than the others.

*“Hoppeedderkopp” by hornet81 is licensed under CC BY-ND 2.0*

These jumping spiders do not spin webs. Instead they use their silk to build ‘retreats’ in high-up places where they can rest safely when not hunting. Once they have spotted potential prey with those amazing eyes of theirs, the spiders go into stealth mode and approach, leaping only when they are close enough, but not before attaching a dragline. And these spiders can jump! They can cover many times their body length in a single leap.

These aptly-named spiders will pounce on and eat flies, bugs, bees and wasps, butterflies, dragonflies, grasshoppers and other spiders. They can reportedly kill prey that is twice their size. They do this by first injecting the prey with venom and then overpowering them by brute force while the prey is still mobile.

Desert Mantis

On October 22, 2020 By Bernadette SimpsonIn Arthropods4 Comments

Camouflaged against the stones and gravel, desert mantises (Eremiaphila spp.) are so cryptic that they are difficult to spot unless they are moving.

They are well-adapted to arid habitats, and there are 31 different Eremiaphila species recorded in Egypt.

Desert mantises are voracious ambush predators, waiting patiently until their prey is spotted and then pursuing their victims quickly and grasping them with their spiked forelegs. Because their hunting relies heavily on vision, desert mantises are diurnal, or active during the day. They are very flexible, able to move their heads without moving their whole bodies, allowing a large field of vision.