Sharp Spray of Water

Nearing the end of August, we're on the downhill slope of summer in Minnesota. Today is the beginning of the great Minnesota get together - the Minnesota State Fair. I am not a frequent or enthusiastic fair-goer. Large crowds and long lines make me feel anxious. I mention it only because the fairgrounds are adjacent to the University of Minnesota St. Paul Campus, where I volunteer.

Today on my bicycle ride to the greenhouse I passed hundreds of cars headed to the parking lots near the fairgrounds. Cycling faster than the traffic was easy since the streets around the fairgrounds were largely grid-locked with cars inching along. Thankfully, the drivers maintained their cool and avoided the temptation to drive in the bike lane - as witnessed last year. I was able to scoot past them and arrive at the greenhouse intact.

My main assignment was climb up on a ladder and use a standard garden hose to spray the leaves of four small trees. The goal was to dislodge insect pests of various types: thrips, mealybugs, scale, spider mites, etc. After cleaning the plants, I use a hand-sprayer of dilute (less than 1%) peppermint and clove oil to coat the leaves. These essential oils are a natural deterrent - non-toxic to humans at low concentrations - to help keep the pests off of the plants. I've written about this subject in the past, and believe it's worth mentioning here again.

The small trees I cleaned treated today are: Passiflora lindeniana, Melaleuca citrina, olive, and lime.

Passiflora lindeniana, popular for its beautiful blossoms

Another assignment I enjoyed today was repotting a couple of small cycad plants. With an ancient lineage dating back to a time before the dinosaurs, the greenhouse has a small but respectable collection of these critically endangered plants. Many of them have struggled to thrive in the greenhouse. However, now a few of them have started to grow well. The hope is larger terracotta pots with well-draining sandy soil will encourage them further, and eventually produce cones.

Collection of endangered cycad plants

Finally, the plant coordinator for the greenhouse introduced me to an unusual plant that has just begun to produce flowers - Ceropegia sandersonii. The flower resembles an open parachute gentle wafting down to earth. It is unusual for its ability to trap flies, forcing the insect to remain in the blossom, unintentionally pollinating the flower as it tries to escape. Eventually, the blossom dries and the fly is able to escape.

New green and white flower of Ceropegia sandersonii, also know as the parachute flower, which is able to trap flies

Ceropegia sandersonii, parachute flower, climbing up a metal hanger

Comments

A Sensitive Plant and Common Weed

Mimosa pudica, also commonly called the sensitive plant was a popular houseplant when I was growing up in the 1970s. It was popular for its ability to quicky change shape by folding up its leaves to protect them from herbivore predators. At the slightest touch the plant is able to expell water from special cells in the leaves, changing the shape from frond-like to a stick-form. The plant creeps along the ground, never for than a foot or so in height. In tropical parts of the world this plant is considered and invasive weed. Today, as I was treating plants to remove pests I happened to touch the leaves of a Mimosa pudica , one with a pretty puff-like flower. Sure enough, the leaves all folded up to almost nothing. Mimosa pudica , the sensitive plant Other more routine chores during my four-hour shift at the U of M Conservatory included cleaning three plants of Hibiscus clayi, native to Hawaii. These three plants in particular have suffered repeated infestations with a variety of in...

Bog Monsters

As a layman of botany the idea of carnivorous plants has perplexed me. The capturing and eating of other creatures seems like it ought to be limited to animals, since animals are mobile and plants are not. Almost all plants survive and thrive in the world through photosynthesis. They do not need to feed on animals to survive. But, what about the group of plants that are carnivorous? As stationary plants, why and how do they eat critters? This topic was stimulated by my assignment today at the Conservatory Greenhouse of the University of Minnesota. My task was to clean several large tanks of water filled with aquatic plants. While cleaning the tanks I realized many of the plants were classified as carnivorous . What is it about the aquatic environment that causes plants to eat - in effect - other creatures? The short answer is carnivorous plants evolved in nutrient-poor settings such as pond water which is naturally low in the amount of nitrogen needed to synthesize proteins. To compens...

Autumn Inside the Greenhouse

I felt the firm grip of fall as I walked the half-mile from the parking lot to the Conservatory Greenhouse at the University of Minnesota, where I volunteer. The temperature outside was in the 30s, and the wind whipped at my face. Yesterday there had been snow flurries. In stark contrast to the outside world, the greenhouse climate was quite different. Part of the greenhouse is maintained at near-tropical temperatures. But other sections of the greenhouse are kept significantly cooler to support plants that have evolved in seasonal climates. Although indoors, autumn has arrived here too. The sunlight dims, and the nights grow long. Inside these cool greenhouse rooms the plants shed their leaves and virtually cease growth for the winter months, just as they would outdoors. Part of my assignment for today included the pruning of yellowing and brown leaves. Removing the dead foliage from the plants and the floors helps to reduce the overall risk of mold and other pests affectin...

City Gardener

Search This Blog