Dr. David Dunn…Because of him, we have the Tucker Greenhouse.

Dr. Dunn taught Plant Taxonomy for years at MU.  He was largely responsible for the design of the Tucker greenhouse.  He collected the majority of the plants now growing in the greenhouse too.  I recently visited with his daughter who shared stories with me of her dad, ‘Doc’, and of plant collecting trips she went on with him and his graduate students all over Mexico & Central America.  This photo of him was taken on one of those many trips.

Dr. David Dunn

My coworker Melody Kroll and I recently went to MU Archives to look at the huge collection housed there of Dr. Dunn’s research, etc.  In a file labeled ‘Plant Collection trips ’69-’71’, I found his hand-drawn phylogenetic trees of various plant families. See two of the best below.

Also, we discovered lots and lots of letters people had sent to him asking for his help in identifying plants.  He was quite well known for his plant identification skills.  He would take the time to ID all the plants people sent to him, and he’d write back a very personal, detailed reply about each plant. There were hundreds of these.  One really stuck out for me.

A woman in New York submitted some leaves to Ralston Purina (the pet food corporation) asking them to ID a plant that her dog kept eating.  She thought that since it didn’t make her dog sick, maybe they should use this plant in their pet food recipe. Ralston Purina sent her letter to Dr. Dunn, and sent the woman a letter telling her that they’d submitted her leaf sample and her letter to a renowned Botanist at the University of MO who was the expert in identifying plants.

Dr. Dunn’s daughter also shared with me that her dad was a frequent guest of a local television show called ‘Of Interest to Women’.  This was a gardening show about spring planting, preparing gardens for planting in fall, and how and when to plant a certain plant.

More to come on Dr. Dunn and his amazing career at MU.


Cacti donations made to the Tucker greenhouse!


Echinocactus grusonii-Cactaceae (Barrel cactus)

This Saguaro is 40 years old. It might send out its first branch in another 20 years.


cactus 2

This Carnegie gigantic is ten years old Cactaceae (Saguaro cactus)

These three cacti were generously donated to the Tucker greenhouse ‘Desert room’ by Dr. Jeanne Mihail from the Plant Science Dept. at MU.  Dr. Mihail grew the smaller Saguaro from a seed!  Dr. Mihail is a mycologist and teaches ‘Biology of Fungi’.

Cool happenings in the Tucker Greenhouse today

Drop in if you get a chance.  The Lithos plants, commonly called ‘Living stones’ are getting ready to bloom.  They’re located in the succulent greenhouse on the south end.

Also, be sure to check out the amazing growth ‘Stinker’ (the titan arum plant) has made this fall.  Stinker is located at the far south end of the greenhouse.

Trialeurodes vaporariorum, better known as ‘those nasty whiteflies’


Ficus leaves damaged by whiteflies

The Tucker Greenhouse has its share of ‘critters’, but right now there is a ‘bloom’ of these nasty whitefly insects, AND they are slowly defoliating a large Ficus tree in one of the tropical greenhouses. They seem to like certain plants better than others too.  They love feeding on members of the Araceae, and Moraceae plant families in particular.

For a great description of whiteflies and the havoc they can wreak on plants, see the following from Planet Natural, a research center for organic gardeners…

 “Common on houseplants and in greenhouses, the whitefly (Trialeurodes vaporariorum) is a sap-sucking insect that is often found in thick crowds on the undersides of leaves. When infested plants are disturbed, great clouds of the winged adults fly into the air. Both nymphs and adults damage plants by sucking the juices from new growth causing stunted growth, leaf yellowing and reduced yields. Plants become weak and susceptible to disease. Like aphids, whiteflies secrete honeydew, so leaves maybe sticky or covered with a black sooty mold. They are also responsible for transmitting several plant viruses. 
Adults (1/16 inch long) are moth-like insects with powdery white wings and short antenna. They are easily recognized and often found near the tops of plants or on stem ends. Wingless nymphs are flattened, oval and almost scale-like in appearance. After the first instar, or crawler stage, they settle down and attach themselves to the underside of leaves and begin feeding.
Young nymphs overwinter on the leaves of host plants. In late spring adult females deposit 200-400 eggs in circular clusters on the undersides of upper leaves. The eggs hatch in 5-10 days and first instar nymphs, which resemble small mealybugs and are called crawlers, move a short distance from the egg before flattening themselves against the leaf to feed. The remaining nymphal stages (2nd, 3rd and 4th) do not move. A non-feeding pupal stage follows and within a week, young adults emerge to repeat the cycle. There are many generations per year. Whiteflies develop from egg to adult in approximately 25 days at room temperature. Adults may live for one to two months.”
Since the Tucker Greenhouse is filled with a diverse group of plants, and since people of all age groups walk through it on a daily basis, I try and limit the use of harmful pesticides.  I do use insecticidal soap, and an occasional systemic insecticide applied to soil, but largely, I depend on beneficial insects to help me combat the vast array of plant feeding insects that visit the greenhouse regularly.  I use lady bugs, mealybug destroyers, and whitefly parasitic wasps.
Today I received a package in the mail of 3,000 Encarsia formosa pupae.  Encarsia is a whitefly parasitic wasp that feeds on whiteflies.
The package of 3,000 pupae was shipped on ice to keep the insects cool during shipment.  So, since these tiny, delicate wasp pupae are one these cards, I’ll be placing them on the branches of plants throughout the tropical room.  Stay tuned for the results!

End of fall semester! What is blooming or fruiting in the Tucker Greenhouse on Stop Day?

pink flower

Billbergia nutans, Queen’s Tears, found in the Bromeliaceae family.

orange flower

Caesalpinnia pulcherrima, Pride of Barbados, found in the Fabaceae family.

white flower

Eucharis grandiflora, Amazon Lily,  found in the Amaryllidaceae family.

maroon seed pod

Theobroma cacao, cacao tree seed pod (chocolate), Malavaceae family.

white flower

Cactaceae family, found in the desert room.

white flowers

Cordyline sp., Giant Palm Lily,  found in the Asparagaceae family.

white orchid

Orchidaceae family.

red flower

Euphorbia pulcherrima, Poinsettia, found in the  Euphorbiaceae family.

pink color

Adenium obesum, Desert rose, found in the Apocynaceae family.

white flower

Pentas sp.,  found in the Rubiaceae family.

pink orchid