I went collecting twice last week without Daniel, who was in Maine on another project. This is a nice challenge for me since I am not as experienced a botanist as Daniel. I can identify many plants and know how to use field guides to learn the ones I don't know, but when Daniel is there, he knows to search for look-alike species that I might not be aware of. For instance, the two Japanese knotweed species he taught me to distinguish: Reynoutria japonica and Reynoutria sachalinensis. (see July entry 79th Street Transverse Road. Note that in the blog I used the old genus name for these species, Fallopia). I did my best and found some good species today and Wednesday.
I met my friend Christina Colón on Wednesday at 103rd and Central Park West. Christina is an ecology professor at Kingsborough Community College. We became friends during the year and a half that I worked there. We walked through the Pool area and into the Woodlands to walk along the Loch and the Meadow.
In the wooded area on the north side of the Pool we found our first few species in a sunny clearing. Giant ragweed (Ambrosia trifida). Although this herbaceous plant is native to North America, most people treat it as a weed. It thrives in disturbed habitats and waste places. The inflorescences are made up of tiny yellow-green flowers that are not showy and have no petals or sepals. This species is wind-pollinated and is one of the main sources of hay fever. This species is what is known as an annual. It completes it life cycle in one year. It germinates from a seed in the spring and grows all spring and summer. By August it forms flowers and then fruits. By the fall when the fruits mature, they release their seeds and the plant dies. But the species lives on in all those seeds that will germinate next spring. Compare this life cycle to biennials and perennials described a little further along in this blog.
The sunflowers and coneflowers have been used as restorations species by the Conservancy and some now regenerate on their own. There is a lovely stand of brown eyed susans, or thin-leaved cone flower (Rudbeckia triloba) along the 102nd Street crossdrive. The photo below shows the flowerheads with the distinctive dark discs of the black- and brown eyed susans. But the leaves in the photo are misleading, they belong to the partridge pea (Chamaecrista fasciculata) which was growing in the same area. The brown eyed susan has variable leaves - the upper leaves are roundish, lower leaves ovate with some having three lobes (hence the name triloba).
On the north side of the 102nd Street cross drive is the Wildflower Meadow. It is the only meadow of any size in the Park. When people talk about conservation and restoration of natural areas, there is a tendency to focus just on woodlands and trees. Biodiversity needs all types of habitats to be preserved. There are species that live only in woodlands, some live only in meadows or wetlands. Some need more than one type of habitat - for example, some bird species feed on the insects and seeds in meadows but nest in wooded areas.
One species we found in bloom in the meadow is the spotted knapweed (Centaurea maculosa). This is a European native that can become a problem where it becomes established. It is a biennial, which means it completes its entire lifecycle in two years. The first year it is a rosette (group of leaves low to the ground) and its function is to photosynthesize and store nutrients in its large taproot. Over the winter, the above-ground part of the plant dies back, but the roots go dormant and survive the winter. The second year, it uses the stored energy in the taproot to produce flowers and fruit. Once the fruit matures, it releases a large number of seeds and then the individual plant dies. The large number of seeds it releases gives it an advantage over other plants. This is a plant I would recommend the Conservancy weed out of the Meadow. But, as I've mentioned before, native or non, invasive or not, I can appreciate the beauty in all plants. Just take a look at this flower.
Obedient plant (Physostegia virginiana) is a fun one to observe. This lovely inflorescence is made up of tubular, lipped flowers that look like little snapdragons. But don't be fooled, it is in the mint family, not the snapdragon family. The fun part comes in when you gently push each flower in any direction. It will stay where you push it, as if it has a little hinge at the base of the flower. (Note to self: make some fun videos to include in the blog!) This North American native is a perennial, so unlike the Centaurea, it will continue to live for more than two years. Every winter, the above-ground parts die, the roots stay dormant and the plant re-emerges in the spring. The total number of years a perennial lives varies with each species. Herbaceous perennials may live from several years to several decades. Woody perennials (trees and shrubs) might live for hundreds of years.
I have written about sumacs in previous posts. Here is another species in the same genus - shining sumac (Rhus coppalinum). The photo below shows you how it got its common name. The flower is an inflorescence made up of tiny greenish-yellow flowers which turn into the easily recognized red fruit of the sumacs. Visit the meadow in the fall to see the brilliant red fall color of this native shrub.
Oaks (Quercus sp.) have easily recognizable leaves and fruit (acorns). But learning to distinguish all the different oak species is not as easy. In my July 22 entry, I mentioned a white oak (Q. alba) we found. That is more likely a swamp white oak (Q. bicolor). Daniel and I will verify. The photo below shows a common oak species found in Central Park, as well as throughout other City parks: the red oak (Q. rubra). The lobes of red oak are bristle-tipped. The acorn is round with a flat brown cap (it looks like it's wearing a little beret). The buds are reddish-brown and cone-shaped. In the winter, when trees are bare of leaves, buds and persisting fruit are how we can identify species.
Last Monday I did a short collecting day in the Ramble. Sweet pepper bush (Clethra alnifolia) is blooming and the fragrance is just intoxicating. One of the sweetest smelling flowers we have, it is a good nectar plant to attract butterflies. It is native to eastern United States and grows in moist to wet soil. This species tends to reproduce by suckering, that is, new plants are produced from root tissue. Since this type of reproduction does not depend on seeds, it is called asexual reproduction (also called vegetative reproduction). The new plants will be genetically identical to the parent plant (clones). The sumacs we have been looking at in these blog posts also reproduce by this method.
Colt's foot (Tussilago farfara) is an interesting member of the Aster family. It is a perennial which spreads by seeds and rhizomes (underground horizontal stem of a plant). The flowers resemble dandelions and emerge in the spring before the leaves. This species has not been documented before as being in Central Park. I remember seeing it some years ago, but only a small group by the Loch. Daniel and I recorded it in the spring when we found it in flower by Glenspan Arch. The group in the photo below is growing along the Lake just north or Bow Bridge. It will be interesting to see if it is growing elsewhere in the Park.