Violaceus euphonia looking for nectar in the avocado tree (Persea americana)

     This time of year, there are a few trees in the Costa Rican exhibit that like to drop some or all of their leaves. It can be kind of embarrassing- and messy- to have trees in a tropical glasshouse without any leaves, but it is completely normal. Many tropical trees lose many, if not all, their leaves for a short period this time of year before putting out a new set of leaves.

    Also, not all of them are completely naked because this is also the time many trees, like the avocado tree on the left, start to flower. It makes perfect sense that trees would flower when there are fewer leaves in the way. Having no leaves when in flower greatly increases the visibility of the blooms so they can be easily seen by pollinators. The nectar feeding birds and butterflies have certainly noticed that the avocados are in bloom and have been spending a lot of time in these trees. I can already see the avocado fruits starting to form.

     In Costa Rica, December to March is known as the "dry season," and this is when many deciduous and semi-deciduous trees and plants lose their leaves (the rest of the year is known as the "green season" or "rainy season"). The sparse canopy in the dry season can reveal plants and blooms that may have been hidden during the green season and can make it easier to spot animals. The rainforest canopies are also painted with color from the showy blooms of trees like the two Tabebuia species pictured below.  Tabebuias are dry season deciduous trees that bloom while completely leafless shortly before leafing out.

Tabebuia impetiginosa	Tabebuia aurea

Posted by Nate Tschaenn 

     One of the benefits tof being a glasshouse specialist that is not listed in my employee handbook is the opportunity to sample a variety of  fruits from the many tropical fruit trees growing in the Costa Rica biome. I’m a big fan of tropical fruits and of free food, so I consider myself lucky. Here are a few of my favorites growing here in the glasshouse.

Peanut Butter Fruit- Bunchosia argentea

    The peanut butter fruit is currently in bloom with, hopefully, a good fruit set to follow. Fruits are orange to red and approximately 11/2 to 2 inches long with a very thin skin. The pulpy inside of the fruit smells and tastes like peanut butter and honey.

 Solanum pseudolulo

This plant is a member of the large and diverse genus containing tomatoes, eggplants, and potatoes, as well as the deadly nightshades. The hairs covering the outside of the fruit can be rubbed off under running water. The texture of the fruit is like a tough-skinned tomato, and it tastes something like an orange with the texture of a tomato. The flowers are specially pollinated by bees. The vibration of the bees wings cause pollen to be released from the stigmas. Since we have no bees in the  glasshouse, I have to act as the bee and release pollen by flicking the stigmas with my finger and transferring it to the pistols in order to get any fruit.

Jabitocaba- Myrciaria cauliflora

This is a small tree with beautiful, smooth, multicolored bark. The fruit and flowers are cauliflorous, meaning they grow directly from woody trunks or stems instead of from the new growth, hence the cauliflora in the Latin name. Round green fruits appear shortly after flowering and grow quickly, turning black when ripe. The fruit is much like a muscadine, which is a very thick skinned grape, but much sweeter like a concord grape and with an odd texture to the pulp. A very attractive tree, especially when the stems are covered in fruit.

    There are quite a few more interesting fruits on display that I could share, such as  like the blackberry jam fruit and ice cream bean, which both taste like their name suggests. Maybe I will blog about some more in the future, but in the meantime why not come and check them out for yourself? Nearly all of the fruit trees are now specially labeled with hand painted, wooden signs.

    The bad news about our tropical trees is that I am unable to grow enough of any fruit to hand out samples to the public. But the good news is that many interesting tropical fruits will grow and fruit in pots as patio plants during the summer and houseplants during the winter. The really good news is that with all the new cultivars being introduced, you can grow more tropical fruits at home than ever. Plants cultivars are being introduced that are smaller and more compact, self-pollinating, slower-growing, heavier-fruiting, and even cold hardy. Dwarf cultivars of plants that may have been too large to keep as a houseplant, such as bananas, guavas, pomegranates, lemons, and oranges, are now available. There is even a cultivar of papaya that produces full-size fruit at only three feet tall!

Caterpillars are eating machines. If they could eat any plant they wanted, our Costa Rica biome would probably be reduced to twigs. Luckily, most butterflies are very host specific, and the caterpillars will only eat the leaves of a few select species of plants, often from just a single genus. We generally avoid planting any of the host plants of the butterflies that we keep. Occasionally I will discover that some species of butterfly has found a newly added plant as an acceptable host plant.

     Passion vine is the host plant of several species of longwing butterflies in our exhibit. For the past few weeks, there have been several passion vines placed on the learning cart in Costa Rica, so visitors are able to see the butterflies laying eggs. The passion vines attract dozens of butterflies and allow the visitors to really see them up close.

     You can also see how much damage the caterpillars do as they munch away all the leaves.  I had to start rotating passion vines onto the cart after the caterpillars completely defoliated the first couple of plants put out. If we were to breed our own butterflies, it would take a whole lot of greenhouse space simply devoted to growing host plants and would be much more costly. As it is, our butterfly pupas come from breeders in tropical countries. They are able to grow host plants much quicker and without the use of greenhouses.  

     The butterflies were so excited to start laying eggs on a fresh passion vine that I had put out, that one of them made a mistake and laid an egg right on my shirt.

- Nate Tschaenn