Even a drizzly December morning can't keep plant people from braving the weather to look at plants with their peers. A small group of us with varying backgrounds met at Haverford College's beautiful arboretum to check out conifers. This workshop was designed to go beyond the basic plant walk and allow attendees to take a closer look at the attributes of each plant and talk with each other about their observations.
The morning started with a stunning specimen that is uncommon in the landscape, Cunninghamia lanceolata. We first observed the plant individually. We wrote or drew our observations about the leaves, leaf attachment methods, fruit, "flowers", bark, overall habit and anything that caught our attention. Attendees were asked to make a private guess as to the identification of the specimen. We then regrouped and started sharing our observations. For Cunninghamia we noted how sharp and large the individual needles were. The needles were also rigid and almost plastic-like. The specimen we were working with was a cultivar with a bluish cast to the plant that distinguished it from another specimen nearby. Observations were shared about the different cone structures on the plant and where they were held. I asked the group if anyone had ever seen this plant before and a few responded affirmatively. All observations were from a botanic garden setting. Finally, we shared our guesses as to the identity of the plant and discussed how we might identify it in the future.
Next we made our way towards the Pinetum. We stopped at the Taxodium allee and repeated the same exercise as above for this specimen. We noted this was indeed a conifer, but a deciduous one. We also noted the etymology of the term "gymnosperm". "Sperm" meaning "seed" and "gymno" meaning "naked". Alix explained that it shares the same roots as "gymnasium" in reference to the trend of early athletics being done in the buff. The group shared personal observations of seeing this plant in the wild in Texas and parts of the Southeast U.S. One attendee, Yuhong, noted that she observed a similar tree growing in China and that her taxon is considered a prehistoric plant. She likely had observed Metasequioa, which indeed has a long history and unique story. We noted that our specimen of bald cypress did not have any knees present and discussed how to distinguish it from a Metasequioa. The needles on bald cypress are much shorter than Metasequioa, the cones are distinct (if present), and bald cypress lacks the "armpits" observed on mature Metasequioa.
We then repeated the same activities for Abies firma, Abies chensiensis, Cedrus atlantica (Blue Atlas Cedar), Pinus densiflora, and Picea sp. We noted the differences between Abies (fir) and Picea (spruce). Fir has flat, blunt needles that attach to the stem with a suction-cup-like structure and form a "v" arrangement when looking down the stem length-wise. The cones of fir are held more upright and fall apart at maturity. Spruce needles are sharper and not flat. The needles attach with a small peg structure or often look like they attach directly to the stem. Spruce cones droop from the plant and stay intact at maturity. The cones are also long and narrow and less woody than a typical pine cone.
Our observations of the majestic Blue Atlas Cedar in the Pinetum included short needles held in clumps at the end of extremely truncated lateral branches. The needles had a bluish cast, were not flat (triangular in cross-section) and the cones were very distinct from other cones we observed (pictured left broken open and closed female cones, right male and female cones).
We quickly went over general observations of pines using a specimen of Pinus densiflora. We noted the needles on pines are held in groups, called fascicles. If you gather the needles in one fascicle together the needles form a perfect circle in cross section. The number of needles per fascicle, five on our specimen, is a great help in identification. The needles on pines are much longer than the other conifers we observed. Most people can easily recognize a pine cone, and these were no exception. These were 3-4 inches long with very woody scales. The seeds are held at the base of each scale and we saw signs of wildlife opening the cones to remove the seed (although we can't rule out the possibility of hungry college students).
Traditional conifer ID classes are taught in many places and help to set the baseline understanding of these plants. Our approach to the Plant ID Meet Up allowed us to take our time really observing each specimen, compare them side-by-side, and be able to discuss our observations in greater detail. Being able to communicate the observations we see when we look at plants and talk out where we disagree is important for plant identification. We hope to run more Plant ID Meet Ups in the future and thank Haverford College Arboretum for sharing their incredible collection with us!