A Trip to the Botanical Garden Herbarium

August 27, 2014

Last week Marie Winn, Ken Chaya and I trekked up to the New York Botanical Garden for a special tour. Daniel Atha was kind enough to show us around the herbarium and describe step-by-step how plant specimens are vouchered. It is a time-consuming process involving several people, but in the end you have a beautifully pressed specimen that can be preserved for hundreds of years.

The herbarium at the New York Botanical Garden is the largest herbarium in the Western hemisphere and the third largest in the World. The herbarium is around 100 years old and contains approximately 7 million specimens from all over the world, the oldest of which date back to the 1760s.

The first stop on our tour was Daniel's office. In earlier posts, I showed how Daniel presses plants in the field. Once in the office, he goes through each specimen to make sure they are laid out properly, so that all features can be seen. Once the specimen is dried, you cannot change the layout, so this is an important step. He also checks to make sure the number allocated to the specimen matches his notes and identification.

Daniel and Marie in Daniel's office at the New York Botanical Garden

To be dried properly, each plant specimen is pressed in a folded sheet of newspaper and sandwiched between two sheets of blotter paper and two sheets of corrugated cardboard. All the specimens collected are then stacked. Moisture moves as a vapor from the plant to the blotter to the cardboard. The stack is put on a dryer so that warm air can pass through the vents in the cardboard taking all that moisture and evaporating it into the air.

Daniel, Marie and Ken stacking specimens

Specimens are sandwiched between blotter paper and corrugated cardboard

Insects and fungi are the nemeses of an herbarium collection. They can destroy specimens in no time at all. In the photo below you can see one such critter that made its way into samples that I collected. Dermestid beetles are a group of beetles also known as carpet beetles, skin beetles, larder beetles. They are scavengers that feed on dried plant or animal tissue. They are very specific about what they feed on. Some species feed on plants, some on mammals, some on birds, etc. This species has a fondness for sunflowers, but will probably feed on other plant species as well. The black specks you see are called frass, (insect poop). The worm-like creature you see is the larvae (young) of the beetle.

Dermestid beetle feeding on my sunflower specimen

Insects and other organisms (such as fungi) are destroyed by placing the dried plant specimens in a freezer that is kept at -40C. Although some species can survive extreme temperatures, they cannot survive the sudden change from room temp to -40. All dried specimens go into this freezer for 48 hours.

Herbarium speciemns throughout the United States are mounted on a standard size sheet of paper (11 1/2 x 16"). The paper is acid-free cotton rag.

The collector of the specimen provides all the information to make a label. These labels include the scientific name of the species, the location where it was collected, the name of the institute that supported the collection, the name of the collector(s) and the date collected. Daniel provides all of this information to his assistant who makes the labels and enters the data into the herbarium database.

The specimen then goes to the mounter. She carefully glues the specimen to the mounting paper. Also glued to the paper are the label and an envelope to hold bits of the plant that might break off. The sheet is stamped with the name of the botanical garden and it is given a bar code. Once the specimen gets photographed for the database, it gets a stamp saying "imaged". After the specimen is mounted, it gets put in the -40C freezer a second time to ensure no organisms survived.

Items, such as fruit, that are too large to mount on the sheet get put in boxes with the same label information and bar code.

A few fresh leaves are quickly dried and preserved in silica to be available for DNA analysis. This also gets the same label information and its own unique bar code.

Tissue preserved in silica for DNA analysis

Information from each specimen is entered into the herbarium database. Also included in the database is a photo of the specimen. To produce the photo, the specimen is placed in a light box that has a camera mounted above. The photos are high resolution and researchers looking at specimens online usually can see enough detail to make a proper identification.

Photos of specimens to be added to database

All collectors must provide all the collection information for each specimen so that labels can be generated. Without this information, the specimen is useless. This is a time-consuming process that sometimes a collector does not get around to doing. In that case, a collection can sit on the shelves of the "cold room" for years or even decades. There are approximately 1 million specimens waiting at any given time to be processed. Garden researchers process anywhere from 10,000 to 30,000 specimens a year.

Collections stored in the cold room, waiting to be processed

Once all of the above steps are completed, the specimen finally gets filed into the herbarium cabinets.

The herbarium itself is an entire building with temperature and humidity controlled rooms. These rooms are lined with cabinets that hold the 7 million specimens. Each cabinet contains samples from a plant family from a specific part of the world.

Inside the cabinets, folders group the plants into genera and species.

As a final treat, Daniel ended the tour by showing us some of the oldest specimens in the collection. He showed us two from Captain Cook's first expedition. James Cook was a British explorer and navigator who made several expeditions around the globe, including the first European contact with Australia and the Hawaiian islands. These specimens were collected during his first voyage which lasted from 1768-1771.

Daniel also showed us a specimen collected by Charles Darwin during the Voyage of the Beagle, 1831-1836. Darwin was an English naturalist and geologist. We know him best for his contributions to the theory of evolution. The voyage of the Beagle lasted 5 years and went mostly around South America.

It is exciting to think that our specimens might be studied by someone interested in the Flora of Central Park two or three hundred years from now.

Some of the oldest specimens in the collection

Ramble and North Woods

August 12, 2014

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.

Ambrosia trifida Asteraceae — *Ambrosia trifida* Asteraceae

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).

Rudbeckia triloba Asteraceae — *Rudbeckia triloba* Asteraceae

Chamaecrista fasciculata Fabaceae — *Chamaecrista fasciculata* Fabaceae

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.

Centaurea maculosa Asteraceae — *Centaurea maculosa* Asteraceae

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.

Physostegia virginiana Lamiaceae — *Physostegia virginiana* Lamiaceae

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.

Rhus coppalinum Anacardiaceae — *Rhus coppalinum* Anacardiaceae

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.

Quercus rubra Fagaceae — *Quercus rubra* Fagaceae

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.

Ramble and Reservoir

August 03, 2014

I failed to write about our foray last week, so I will add it to today's post. The 23rd was a short walk in the Ramble, not too many species seen.

The Oven is a nice birding spot in the Ramble just south-west of the Boathouse. There is a beautiful rock outcrop on which one can stand and look into a swampy wooded area and see some of the many species of birds that live in and migrate through the Park. We examined the plants growing in the cracks of the rocks and collected several specimens of the grass family (Poaceae).

Panic grass (Panicum sp.) and rosette grass (Dichanthelium sp.) are similar genera and used to both be classified as Panicum. Like all grasses, they have hollow stems and joints along the stem. The mnemonic "sedges have edges, rushes are round, grasses have knees all the way to the ground" helps to remember this characteristic.

Gleason and Cronquist's Manual of Vascular Plants* lists 48 Panicum species for the Northeast. This edition was written before Dicanthelium was split off. Daniel and I have collected 14 specimens in these two genera. Tune in to future posts when we determine which species we have. In the meantime, here is generally what the two genera look like.

Dichanthelium sp. Poaceae — *Dichanthelium* sp. Poaceae

Panicum sp. Poaceae — *Panicum* sp. Poaceae

We collected arrowwood viburnum (Viburnum dentatum) already, but today we saw a nice stand of it in fruit. The viburnums are shrubs with opposite leaves. Arrowwood is a native species with beautiful black fruit that is attractive to wildlife. The fruit contains a high percentage of fat which is an important energy source for migrating birds. It has always been a good restoration species for the Park as it grows easily and until recently had not serious pest problems. But the viburnum leaf beetle (Pyrrhalta viburni) showed up in the Park within the last 10 years and some of the shrubs have shown signs of beetle damage. Let's hope it does not decimate the populations of arrowwoods we have. Viburnums were formerly classified in the honeysuckle family (Caprifoliaceae), but have been moved to the Adoxaceae. The specific epithet (the second part of the scientific name) "dentatum" refers to the toothed margins of the leaves.

Viburnum dentatum Adoxaceae — *Viburnum dentatum* Adoxaceae

On the 30th we walked around the Reservoir. Daniel had seen a couple of species from prior lists but not yet collected by us and we have not seen those species elsewhere in the Park. Conservancy staff helped us with plants that were out of our reach. We are grateful to Maria Hernandez (Director of Horticulture), Bill Kearny (Reservoir Supervisor) and Andrea Gaskin (Reservoir Zone Gardener) for their help. Ken Chaya and Marie Winn joined us today.

The plants on the reservoir wall are a mix of wild plants and plants that have been seeded in by Conservancy staff. Woody material has to be kept off the wall to prevent damage, so herbaceous plants are encouraged to provide habitat for wildlife.

The first species we collected was lance-leaved coreopsis (Coreopsis lanceolata). This species is native to central and southeastern United States, although it does just fine in our area. This member of the aster family thrives in poor soil as long as there is good drainage.

Coreopsis lanceolata Asteraceae — *Coreopsis lanceolata* Asteraceae

Yellow sweet clover (Melilotus officinalis) is probably found elsewhere in the Park, but so far this is the only group we have come across. It has yellow flowers and compound leaves that are typical of the bean family. A Eurasian species that seeds readily, it is considered invasive in some habitats.

Melilotus officinalis Fabaceae — *Melilotus officinalis* Fabaceae

We found a few other species along the path of the Reservoir. The photo below is of bladder campion (Silene vulgaris). Notice the balloon-like calyx. The calyx is what the collection of sepals is called, the outermost structures in a flower. There is a native campion (Silene stellata) that has a swollen calyx also, but can be distinguished because it has fringed petals. The species we found has only small notches in the petals.

Silene vulgaris Caryophyllaceae — *Silene vulgaris* Caryophyllaceae

There are 5 species of copperleaf listed in Gleason and Cronquist, we have found at least two of them. Today Daniel noticed a third growing along the Reservoir path. This new record for Central Park was first documented in the Northeast by Thomas Delendick in 1990 (http://goo.gl/tYQEXq). He found a few plants growing along the sidewalk in front of a brownstone in Park Slope, Brooklyn. It has since spread to all five boroughs and beyond. (http://goo.gl/JX0nx1). Acalypha australis. We will have to keep an eye out to see how common it is in the Park.

Acalypha australis Euphorbiaceae — *Acalypha australis* Euphorbiaceae

In my post about the 79th Street transverse road, I spoke about the far eastern smartweed, Persicaria extremiorientalis. There is a large, robust stand of it growing at the north end of the Reservoir.

Persicaria extremiorientalis Polygonaceae — *Persicaria extremiorientalis* Polygonaceae

Finally, I will leave you with a photo of a common plant we have already seen in these blog posts, common milkweed (Asclepias syriaca). Part of what is fun about this project is looking for new and interesting plants, but I have to say, I never get tired of the common species. This is a beauty of a native, important host plant for the Monarch butterfly caterpillar and that seed pod is just spectacular. Look closely and you will see a small lady-beetle, probably feeding on aphids which are feeding on the sap of the milkweed. Ordinary is not necessarily dull.

Asclepias syriaca Asclepiadaceae — *Asclepias syriaca* Asclepiadaceae

*Manual of Vacular Plants of Northeastern United States and Adjacent Canada, second edition by Henry A. Gleason and Arthur Cronquist, published by the New York Botanical Garden, 1991.

A Trip to the Botanical Garden Herbarium

Ramble and North Woods

Ramble and Reservoir

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