Monday, October 26, 2009

A Weekend With Petrocosmea

Autumn is my favorite season. Here in the northeast, it can be a spectacularly beautiful time as the trees and shrubs outdoors begin to show vivid colors. The blue sky outside my front door is framed with the most brilliant golden yellow leaves of the maples in all directions. While cooler weather and fall color marks the end of the growing season for the gardens outside, for Pet lovers, it marks the beginning of the heaviest period of bloom for many of the species. This autumn has been a beautiful one and a busy one, so far.

The photo above is a scene from Lewiston, NY, on Goat Island at Niagara Falls. This past weekend, I was priveleged to spend an entire weekend studying Petrocosmea genetics! (with a brief side trip to "the Falls". ) I must keep you in suspence a bit longer, but we are getting some interesting data on the interspecific relationships of the Petrocosmea species we have in cultivation at this time. This information will hopefully contribute some valuable data to our knowledge of this fascinating genus that is still largely unstudied. Of course, the taxonomic component still needs a lot of work, and we are slowly but surely working on that too.

Having access to a microscope allowed me to spend some time studying the anatomical and structural characteristics of Pet species. I could spend months just looking down those lens and gazing at the minute, and miraculous features of each species. Above are some quick, ten-minute sketches I drew of the anthers and filaments of P. nervosa and P. minor-smooth leaf form. The pollen is stored within two "pillow-like" cavities on either side of the mid-line of each anther. The pollen "shoots" out of an opening at the tip (pointed area) when pressure is applied to the "pillow". The shape of the anthers is one of the features that determines species' placement within the three Sections of the genus Petrocosmea. The more rounded shape of the tip of the anther of P. nervosa place it in the most primitive section..Section : Petrocosmea. The pointed tip of the anther of P. minor "likely" places it in Section : Anisochilus (that is my guess). The filaments of P. minor were thick and globular, with a white apex and deep blackish purple violet base. The tiny hairs on the filament were white, with purple tips on the white apex.....the pigments in the filament looked like little purple jewels under the microscope. Amazing and very beautiful!!!

As you can see from the drawing above, two things are evident. First, I am NOT an artist!! and second, there is much to learn from the differences in the anatomical structures of Petrocosmea. I hope to spend much more time in the next few months attempting to iron some of the mysteries and frustrations with the mis-labeling of species and perhaps even confirm that we have some unidentified (undescribed) species within our collections! For me, sketching and drawing the floral parts allows me to focus on every minuted detail. It is a trick I learned as a nursing student many years ago. As I draw, I notice things that I had never noticed before. Try it with your own Pets when they flower. Remove a leaf or a peduncle and spend a few minuted dissecting the structures and studying them. You'll gain a renewed appreciation for the miracles of nature and Petrocosmea!

Excitement continues in the plant room with all of the seedlings coming into first flower. The latest seedling to flower from the cross P. 'Asa Blue' x begoniifolia. Again, something new! This flower has some reddish and pinkish pigment. Note the reddish pigment in the upper petals near the base and at the base of the throat. (The picture doesn't do it justice!). This flower is quite large...the largest so far, and the petals are very broad and rounded with an unusual "serration" along the margin (I have no idea where that came from??!!) A different shape than any of the Pets we have so far. While the plant is still tiny, it is putting out a great number of buds.

The new seedling, (left) with a sibling (right...the more typical shape so far), to show the different shape of the new flower. The flower is large, and the peduncle is nice and short, and strong. This one has a lighter pinkish color also, sort of mauve in color. It definately deserves to be kept for further evaluation. Foliage has a nice purple band around the can be seen in this photo.

Photo of P. nervosa in flower. I love this species. The blue flowers floating above the silvery leaves.
One last comment that I keep getting lots of questions via email about. Shallow pots. Let me just say, if you are struggling with growing first bit of advice is always... "Shallow pots, shallow pots, shallow pots!!!". Once after giving a talk where I had just advocated and preached the virtues of using shallow pots for Petrocosmea culture, a lady came up and proudly announced that she NEVER used shallow pots and her Petrocosmeas won awards all the time in standard pots. She was quite proud of herself and her Petrocosmeas and wanted to let me know that I was mistaken. It was a fun conversation and I got a chuckle out of it. YES, Petrocosmea can be grown very well in standard pots. I'm sure prize-winning specimens could be grown in pots three feet deep if one wanted to adjust culture to accomodate this. But, in my experience, shallow pots prevent a lot of extra effort and disappointment from root rot when the large volume of soil results in soil staying damp for too long. Shallow pots, allow more air to get to the roots, more horizontal room for the shallow and wide root system to roam and great evaporative surface area to increase humidity, keep roots cool, and again, allow soil to dry quickly after watering. They just work better for me. I've used them in the humid and hot south of the USA, the mountains of West Virginia, and now the cooler climate here in Pennsylvania. I use them in windowsill culture and under lights, with top watering, bottom watering, mat watering and wick watering, all with better results than I get from a taller, deeper, narrower standard pot. And, the plants seem to shape up better, with nicer symmetry with the wider diameter of the shallow pots or "pans" as they are usually called. But, to answer the question I keep getting, YES, Pets can be grown quite successfully in standard pots as long as one is cautious of the potential for root rot. As for me, I'll use shallow pots.