Archive for the ‘Sensitive Plant’ Tag



Day by day the rains lessen.  Day by day the sun is breaking through a little more, warming up the ground and consequently the air.  Evaporation causes the relative humidity to rise.  We are almost there, almost into the dry season.  It won’t be long before we start to lament the lack of precipitation but let us at least enjoy the first few dry weeks without complaint.  There were five days with almost no rain but it was a false start to the dry season, the rain returned, not heavily, but rather  grey days with drizzle.

Coloring Time

The increasing temperatures and decreasing precipitation seem to have stimulated flowering in at least some of the plants.  There is one small bush that has produced a display of flowers.  It has the captivating name of Yesterday, Today and Tomorrow, (Brunfelsia grandiflora).  The name refers to the rapid color change in the flowers.  When the bud bursts and the new flower blooms, it is a light lilac color.  By the following day the hue will have started to fade and then several days later the now white flower falls from the bush.

Yesterday, Today and Tomorrow Purple flower.

Yesterday, Today, Tomorrow, (Brunfelsia grandifolia). Flower

Yesterday, Today and Tomorrow is native to the northern part of South America.  It belongs in the nightshade family; Solanaceae.  It is planted in many Costa Rican gardens to provide a showy display of changing colors.  The flowers are also fragrant and attract bees.

Color Sensitive

Many people are familiar with the Sensitive Plant, (Mimosa pudica).  It has the entertaining habit of closing its leaves on contact or as night falls.  It is a very low growing plant found sprawling along the edges of paths and roads.  It is a native to Costa Rica but has now been naturalized in many tropical areas around the world.

The short-lived flowers are a deep lilac fused with red and are pollinated by bees.  But the most intriguing thing about the Sensitive Plant is the ability of the leaves to fold up.  At night the plant exhibits a behavior known as nyctinastic movement.  As the sun sets are darkness envelopes the forest, the leaves of the Sensitive Plant fold and close together.  As the sun rises, they open up again.

Flower of Sensitive Plant, (Mimosa pudica)

Sensitive Plant, (Mimosa pudica). Flower

But more familiarly, if touched the leaves immediately close, a phenomenon known as seisonastic movement.  The means by which this happens is fascinating.  Contact with the leaf causes an electronic impulse to be passed along the leaf which in turn stimulates the transfer of potassium out of the cells at the base of the leaf which then lose water and become flaccid and collapse.  This is an energy expensive reaction from the plant to external contact and therefore must convey some benefit.  As of now, we are not entirely sure what this benefit is.  It could well be that it makes the leaf less appealing to herbivores or when it rains reduces potential damage by being smashed against the ground.  Whatever the reason it certainly compels people to tap it and watch the response.

The Sensitive Plant is also an important nitrogen fixer.  It releases a compound from its roots that inhibit certain pathogenic fungi growing near its roots.  The roots have nodules which contain nitrogen fixing bacteria.  The bacteria do something the plant cannot, they take atmospheric nitrogen and convert it into a form usable by the plant.  Plants require nitrogen for many aspects of their lives, not the least of which being the growth of tissue.  Up to 60% of the Sensitive Plant’s nitrogen requirement is provided by the root-dwelling bacteria which allow it to thrive in areas where the soils are nitrogen deficient.

Purple Rain: Lavender and Lilac Light Up The Forest

There are several other small herbaceous plants that can be seen on the forest floor or around the gardens that have lavender or purple coloration.  Here and there an isolated small purple bell-shaped flower can be found.  The small bloom stands out in contrast to the deep green of the surrounding vegetation.  This is Monopyle sp of the family: Gesneriaceae.  Growing in the same localities but with a larger, shrubbier aspect is the Portaweed, (Staphytarpheta frantzii), which is in the family: Verbenaceae.  The butterflies, particularly skippers, seem to be attracted to the Portaweed flowers.  Both of these plants are native to Costa Rica.

Flower of Monopyle sp

Monopyle sp. Flower.

Portaweed, (Stachytarpheta frantzii). Flower

Portaweed, (Stachytapheta frantzii). Flower

Whereas both of the above plants are low growing and herbaceous, there is a tree that produces a spectacular display of flowers in the canopy, so much so that they are planted in Costa Rican town streets for their attractive blaze of color.  These are the Jacarandas.  When the flowers finish blooming they fall to the ground and cover the forest floor in a carpet of purple.  A native Jacaranda in the forests of the Osa Peninsula is Jacaranda copaia, family: Bignoniaceae.  When it does flower, the canopy is enriched with its pigmented presence.  Afterwards, it provides a brief but colorful change to the normally dull red mud of the forest trails.

Jacaranda, (Jacaranda copeia). Flower.

Jacaranda, (Jacaranda copeia). Flower.

Too Blue To Be True

Flowers tend to divide into 3 distinct classes with regard to color; red, orange and yellow or pink, lilac and lavender or white, cream and green.  The different colors favor different types of pollinators.  Red, orange and yellow attract birds, namely hummingbirds, pink, lilac and lavender are visited by insects, particularly bees, finally whites, creams and greens normally have nocturnal pollinators such as bats and hawkmoths.

The different colors are produced by different pigments.  Plant pigments fall into four categories.  Chlorophyll is a name most people will be familiar with, certainly to some level.  It is responsible for the vitally important green coloration of plants.  Carotenoids give rich reds, oranges and yellows.  Flavonoids give the deep red/purples as well as blacks, browns and white.  Betalains produce red/violet and orange/red.  Things are not as simple as outlined above as there are many overlapping shades and hues.

The one color noticeable by its absence is blue.  Blue is not a common color in plants or animals.  Less than 10% of the named 280,000 species of flowering plants are blue in color.  Plants that have blue flowers have done so with a little bit of manipulative trickery because there is no true blue pigment found in plants.  Anthocyanins are a flavonoid pigment responsible for many red flowers and fruits.  By mixing some of the pigments and altering the pH a blue color is produced.  This produces some spectacular blooms such as Bluebells, Delphiniums and Morning Glory.

Hovering Over Sensitive Changes   Leave a comment

Felipe del Bosque Blog November 18th 2013

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Trying Times

This week started as the last week ended with lots of rain.  Previously the rain had been falling at night but over the first few day of this week it started pouring day and night.  Then a profound change occurred the sun came out and continued to return every morning to give us three days of beautiful dry conditions.

The transitional period between wet and dry season certainly make predictions difficult.  Many aspects of plant and animal behavior rely on abiotic  or environmental cues.  Once we move into the dry season those changes will stimulate many of the plants to flower.  Consequently there will be a lot of hummingbird, bat and insect activity around the nectar producing blooms.  But as yet we are waiting for that change to occur.

Present and Correct

It has been quite a quiet week as far as mammal sightings are concerned.  All the four species of monkey were spotted at many points around the grounds.  Agoutis, (Dasyprocta punctata), can be seen on a daily basis near the Bosque restaurant.  One was seen with a baby this week.  Red-tailed Squirrels, (Sciurus granatensis), can be seen around the open areas of the lodge while Alfaro’s Pygmy Squirrel, (Microsciurus alfari), can be found without too much searching in the forest.  These plain brown, sparse tailed, small chipmunk sized squirrels hop around at low levels of the forest and more often than not will cling head down on the side of a tree trunk and chatter ferociously at you.

Sing For Your Supper

The migrant birds, many of which are tanagers and warblers are still arriving.  Summer Tanagers, (Piranga rubra), have set themselves territories in the gardens in front of the restaurant.  Here they are joined by Cherrie’s Tanagers, (Ramphocelus costaricensus), males with their bright scarlet rumps being followed by harems of orange-brown females.  Up in the branches of the trees are noisy flocks of Golden-hooded Tanagers, (Tangara larvata).

The army ant swarms continue their relentless marches through the forest at several locations on the property.  They attract a lot of attendant bird life, many species of woodcreeper, trogons and of course the ever present Grey-headed Tanagers, (Eucometis penicillata).

Flying in the Face of Confusion

The migratory Green Urania, (Urania fulgens), moths are continuing to build in numbers.  Butterfly numbers increase when the sun is shining but it will be several months before they hit their peak.  Around the pond the dragonflies are starting to be seen more frequently, the bright blues and reds of these agile aerial hunters dart to and fro before settling momentarily of a leaf.  Their heads turn this way and that, the acute vision with which they are gifted allows them to see predator, prey, mates and rivals, the presence of which causes the observer to react very quickly.  Predators they avoid, prey they will catch, mates and rivals they will chase.

Within the darker confines of the forest flies an insect that both mesmerizes and inspires awe in those seeing it for the first time.  Damselflies would be considered by most as being the smaller, more delicate relatives of the dragonflies.  Here in the forests surrounding Bosque del Cabo  flies the largest damselfly on the planet, the Helicopter Damselfly, (Megaloprepus caerulatus).

Megaloprepus caerulatus

The first words used by guests upon returning from the forest where they have witnessed this spectacular creature for the first time are “I saw something flying like a helicopter”, or there were two large insects flying round each other.

The body is long and needle-shaped.with a broad tip.  The wings are heavily veined and made of thin transparent tissue like clear cellophane.  As the creature flies the wings catch the light and glint in the sun.  But the confusing part about what is being seen is in no small part due to the bluey-black and silver-tips to the end of all four wings.  When in flight they give the impression that the wings are moving in the same fashion as the rotor blades of a helicopter, hence the name.

The Helicopter Damselflies are spider-eating specialists.  They have the ability to fly vertically up and down as well as horizontally in and out which you will see them do in front of a series of spider webs.  When they find the silk spinner, they grab it in their legs, reverse backwards, nip of the head and legs then proceed to devour the softer body parts.

It is not uncommon to see the Helicopter Damselflies along the trails but it is not the easiest insect to photograph.  When at rest they fold their wings back and over the body.  This is your opportunity as it was mine.  There is a smaller species, Mecisogaster ornata, which is also frequently seen and has yellow tips to the wings.

Little Flower

This week I decided to take a look at and photograph some of the plants that grow next to the roadside and are so often ignored.  They are there every day and most flower continuously year round but everyone just walks by and doesn’t notice.  But if you sink to your knees and go down to their level then you will see that they are just as pretty as the large showy blooms sported by many of the shrubs and trees..

One low growing herbaceous plant with deep green foliage offsetting its tiny yellow flowers is the Florecilla, (Baltimora recta).  It belongs in the daisy family (Asteraceae).  Another plant is the same family is the Dandelion, (Emilia fosbergii).  It is not a plant native to the Americas, its origins belong in the Old World, but now its delicate pink and purple flowers can be seen decorating any sunny roadside throughout the country.

Baltimora recta         Emilia fosbergii         Sida rhombifolia

There are several sprawling ground huggers to be found everywhere on the Bosque verges.  One has small yellow cup shaped flowers, Escobilla, (Sida rhombifolia).  This plant is found all over the planet in tropical and subtropical open areas.  Being so common you would think it would be familiar to a lot of people but probably only the discerning botanist would notice it.  In many situations growing beside the Escobilla is a plant with small pink pom-poms as flowers.  It is not the flowers that normally catch the attention with this plant but rather the leaves.  When touched, the leaves instantly fold up and the stem droops.  The reason for this is not entirely understood but there are several theories.  It could be to escaped grazers but I can’t see why a folded leaf would not be consumed over an open leaf.  When it rains the pounding of the droplets may damage the leaf so again it folds.  Finally at night the leaves close.  This may aid in reducing transpiration but once more in the evening when the temperature drops, the relative humidity of the air increases so I am not sure about that one either.  Nonetheless it certainly remains a feature that in particular fascinates children.

Mimosa pudica

Philip is a biologist, writer and photographer at Bosque del Cabo Rainforest lodge on the Osa Peninsula, Costa Rica.

Text and Photographs are taken from the forthcoming book:

The Natural History of Bosque del Cabo by Philip Davison

Temperature and Rainfall

Average Daily Rainfall 0.37 ins.  Total Weekly Rainfall 2.61 ins

Average Daily Rainfall 9.50 mm.  Total Weekly Rainfall 66.3 mm

Highest Daily Temp 89°F.  Lowest Daily Temp 74°F.

Highest Daily Temp 32.2°C.  Lowest Daily Temp 23.7°C.

Species List for the Week


  • Central American Squirrel Monkey
  • Mantled Howler Monkey
  • Spider Monkey
  • White-faced Capuchin Monkey
  • Common Tent-making Bat
  • Central American Woolly Opossum
  • Agouti
  • Red-tailed Squirrel
  • White-nosed Coati
  • Collared Peccary


  • Red-lored Amazon
  • Scarlet Macaw
  • Great Curassow
  • Black Hawk
  • Black-hooded Antshrike
  • Chestnut-back Antbird
  • Common Paureque
  • Lineated Woodpecker
  • Pale-Billed Woodpecker
  • Blue-crowned Motmot
  • Short-billed Pigeon
  • Long-billed Hermit
  • Purple-crowned Fairy
  • Stripe-throated Hermit
  • Red-capped Manakin
  • Streak-headed Woodcreeper
  • Wedge-billed Woodcreeper
  • Fiery-billed Aracari
  • Chestnut-mandibled Toucan
  • Summer Tanager
  • White-shouldered Tanager
  • Bright-rumped Atilla
  • Dusky-capped Flycatcher
  • Golden-crowned Spadebill
  • Great Kiskadee
  • Great Tinamou
  • Black-throated Trogon
  • Black Vulture
  • Turkey Vulture


  • Basilisk
  • Cat-eyed Snake
  • Central American Smooth Gecko
  • Clawless Gecko
  • Common Anolis
  • Four-lined Ameiva
  • Golfo Dulce Anolis
  • Mediterranean House Gecko
  • Terciopelo


  • Banana Frog
  • Black and Green Poison Arrow Frog
  • Fitzinger’s Rain Frog
  • Masked Smilisca
  • Marine Toad
  • Red-eyed Green Tree Frog
  • Savage’s Thin-fingered Frog
  • Stejneger’s Dirt Frog
  • Tink Frog


  • Anartia fatima
  • Anartia jatrophae
  • Cithaeria pireta
  • Dione juno
  • Dryas iulia
  • Eueides aliphera
  • Eueides lybia
  • Glutophrissa drusilla
  • Heliconius erato
  • Heliconius ismenius
  • Heliconius sapho
  • Heraclides cresphontes
  • Junonia evarete
  • Morpho helenor
  • Morpho menelaus
  • Parides erithalion
  • Perophthalma lassus
  • Pierella luna
  • Pyrgus oileus
  • Pyrisitia nise
  • Saliana esperi
  • Urbanus simplicius


  • Acmella oppositifolia Flowering
  • Allamandra cathartica Flowering
  • Alpinia purpurata Flowering
  • Anthurium salvinii Flowering
  • Apeiba tibourbou Flowering and Fruiting
  • Aphelandra golfodulcensis Flowering
  • Arachis pintoi Flowering
  • Arundina graminifolia Flowering
  • Attalea rostrata Fruiting
  • Baltimora recta Flowering
  • Bauhinia variegata Flowering
  • Brunfelsia grandiflora Flowering
  • Calathea marantifolia Flowering
  • Cananga odorata Flowering
  • Canna sp Flowering
  • Cascabella thevetia Flowering and Fruiting
  • Castilla tunu Flowering
  • Chrysobalanus icaco Fruiting
  • Citrus spp Flowering and Fruiting
  • Clusia rosea Flowering and Fruiting
  • Clusia valerii Flowering
  • Cocos nucifera Flowering and Fruiting
  • Costus speciosus Flowering
  • Couroupita guianensis Fruiting
  • Cresentia alata Flowering and Fruiting
  • Crotalaria retusa Flowering
  • Cyclanthus bipartitus Flowering
  • Emilia fosbergii Flowering
  • Etlingera elatior Flowering
  • Guaterria amplifolia Fruiting
  • Hedychium coronarium Flowering
  • Heisteria accuminata Fruiting
  • Heliconia chartacea Flowering
  • Heliconius clinophylla Flowering and Fruiting
  • Heliconia latispatha Flowering
  • Heliconia longiflora Flowering
  • Heliconia pogonantha Flowering
  • Heliconia psittacorum Flowering
  • Heliconia rostrata Flowering
  • Hibiscus rosa-sinensis Flowering
  • Hymenaea coubaril Fruiting
  • Ixora coccinea Flowering
  • Lantana camara Flowering and Flowering
  • Mimosa pudica Flowering
  • Morinda citrifolia Flowering and Fruiting
  • Musa acuminata Flowering and Fruiting
  • Pandanus sp Fruiting
  • Piper hispidum Flowering and Fruiting
  • Pleiostachya pruinosa Flowering
  • Plumeria rubra Flowering
  • Psychotria solitudinum Fruiting
  • Sida rhombifolia Flowering
  • Spathodea campanulata Flowering
  • Spondias mombin Flowering
  • Stachytarpheta sp Flowering
  • Thunbergia erecta Flowering
  • Thunbergia fragrans Flowering
  • Tocoyena pittieri Fruiting
  • Virola sebifera Fruiting
  • Zingiber spectabile Flowering
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