Ecuador: The Galapagos II. Plants

On my recent trip to the Galapagos I joined park rangers on hikes, and usually I was a laggard. I kept  stopping to see the plants. The rest of the group hopped from one animal photo op to the next. I tried to keep up but did a bad job of it.

the endemic tree cactus Opuntia galapagela

Just like its  animals, the Galapagos's plants include many that are unique and that differ from their mainland relatives and between islands. 

My tour (Minnesota Landscape Arboretum, Knowmad Adventures and GoGalapagos cruises) only had time for five islands and was not focused on plants, so I can't show you plant variations, which are part of what makes the Galapagos special. However, these are dry volcanic islands close to the Equator, so their vegetation was fascinating. 

The coastal zone is rocky with lava rocks that are millennia-old, but in the dry climate, have not broken down much. The plants that spread over those rocks are usually thick-leaved succulents, conserving water and enduring salt.

 

portulaca, Portulaca species

Some are common plants from around the world, for example, portulaca (Portulaca oleracea, portulaca family Portulacaceae) and sea purslane (Sesuvium portulacastrum, ice plant family, Aizoaceae) and yet often, as is the case for Portulaca and Sesuvium, they have closely related species that are unique to the Galapagos. I needed more time and better books to identify the natives.

sea purslane (Sesuvium portulacastrum)

A bit farther inland, the sandy or gravelly soil supports a wider range of plants. Puncture vine (Tribulus cistoides, puncturevine family, Zygophyllaceae, below) looked very like its relative from sandy soils in Nebraska. It is a common plant of trampled areas in the American tropics. The yellow flower is pretty but the seed comes in a hard green spiked fruit, tough enough to puncture bicycle tires. I did not see ripe fruits when I was there in early May.

Puncture vine (Tribulus cistoides)

Another plant that I saw I thought was the widespread shrub lantana, Lantana camara (vervain family, Verbenaceae), which has very attractive flowers in many colors but has become an international weed. However, when I looked it up, I found the white flowered lantana of the Galapagos is Lantana peduncularis which is endemic to the Galapagos. Really a pretty plant.

lantana  Lantana peduncularis

Ground cherry, Physalis (tomato family Solanaceae), below, was familiar to me because there are numerous species native to North America. However, the Galapagos has three species considered native, Physalis angulata, Physalis cordata and Physalis pubescens as well as a recent invading species, Physalis peruviana. The one in my photo was common close to the rocky shore, but I do not know which species it is. 

                                                      ground cherry, Physalis species

Farther back from the coast, there were shrubs taller than I am, with round bright green leaves and dramatic yellow flowers. This was yellow cordia, Cordia lutea (borage family, Boraginaceae), a plant of the Pacific Coast of South America that I first saw in Costa Rica in the 70s. They were not flowering much when I saw them, so my photo does not do it justice, because the livid yellow blossoms can cover the whole top of the plant. 

 

 

 

 

yellow cordia, Cordia lutea 

These are two small plants of senna, Senna pistacifolia (pea family, Fabaceae), but they grew to be tall trees. The flowers are a bright yellow and you can see the long thin pods developing. Found in South America, they are considered native to the Galapagos, where they are common.

 

senna, Senna pistacifolia 

There were also great stands of grasses. The Galapagos has only one native grass (plants in the family Poaceae), and it is confined to new lava flows on the western islands. So all the grasses I saw, and there were easily six common species, were introduced. I thought it intriguing that there were lots of portulacas and ground cherries and only one grass, because around the world, grasses are spectacularly successful, both common and with many different species. I speculated that in this tropical environment without major grazing animals, their advantages--growing point underground, low nutrition in the leaves--do not give them the usual edge.  (post about grasses: link)

common grass

 And there were plants that every botanist wants on their life-list. First, a handsome endemic cotton, Gossypium darwinii (hibiscus family, Malvaceae). These were shrubs six feet high, with these beautiful yellow flowers. They were quite common in some areas. Wonderful. 

 

 

 

Galapagos cotton, Gossypium darwinii

And woody plants in the sunflower famly. Though a huge worldwide family, the Asteraceae is almost entirely herbaceous. The Galapagos is unusual in having shrubs and trees in that family, endemic of course. This is Trigonopterum larcifolium, endemic to Ecuador. I saw it planted in a reserve but it is described as widespread. So not quite "in the wild" but in its native region. This photo doesn't do it justice; it is a scruffy shrub, woody and about 6 high, with cute daisy-like flowers hanging off the ends of the branches.

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a composite (sunflower family Asteraceae)
that is a woody shrub, Trigonopterum larcifolium

The Galapagos was beautiful. Often large areas were covered by the same species, good for identifying a plant and, then, finding another, practicing the identification. Many were Galapagos species in familiar American genera, so they looked like something I knew. But, were a Galapagos endemic and so, something I'd never seen before. So much fun!

 

 

Comments and corrections welcome. 

 

References 

Darwin Foundation website https://www.darwinfoundation.org/en/ A searchable database to check or help identify Galapagos animals and plants.

Scholfield, E. K. 1984. Plants of the Galapagos Islands. Universe Books, New York. Many of the names have changed but the sketches and descriptions are very helpful.  

 Kathy Keeler

A Wandering Botanist

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