One of the best parts of working on the Central Park Flora Project has been the many wonderful people with whom we get to collaborate. My last post was titled "Scavenger Hunt" and in it I included a list of species Daniel and I are still trying to locate for our project. Within a few weeks we were contacted by several of our colleagues who had spotted a few species from the list and even told us about new ones for the project!  

This first species pictured below is Sisyrinchium angustifolium, narrow-leaf blue-eyed-grass. Although this native species looks like a grass, it is a perennial in the Iris family. Each plant grows to about 30cm (1 foot) or less. The flowers are small, 6mm (1/2 inch) with 3 sepals and 3 petals that are blue-violet and identical to each other. The fruit is a capsule that will split and release 3 black seeds. 

We were alerted to this plant by our colleague Eve Levine. Another colleague, Richard Lieberman had shared our list with her and she remembered this plant growing in the Ramble, so she set off to relocate it. She found it growing at the base of a London Planetree at the Tupelo Meadow. It is interesting to note that this is barely a meter away from where I found this same species in 2007. So far, we have not seen this species anywhere else in the Park. Is it the same or a descendant of that individual from 2007? There is no way to know, but it is gratifying to see that the species is persisting in this unlikely location - the base of a tree on a mowed lawn.  

Sisyrinchium angustifolium Iridaceae. In fruit. Photo by Ken Chaya

Eve also gave us a location for Anemone virginiana. This can be found at the base of the stairs that go from the Castle to the Shakespeare Garden.  This member of the Buttercup family has flowers made up of 5 white sepals, which look like petals. The seedheads you see in the photo below will eventually release a white cottany mass that will carry the seeds in the wind. Based on the notes included on the 2007 herbarium specimen, this species was collected from the same location at that time. While it may have been planted here originally, it is definitely reproducing on its own and fully naturalized.

Anemone virginiana Ranunculaceae. In fruit. Photo by Ken Chaya

The next two species were found by Conservancy staff John-Paul Catusco and Eric Whitaker. They found Chimaphila maculata, a member of the Heath family near Azalea Pond in the Ramble, identified it and emailed Daniel and me to see if we had it for our list yet. We did not! These are spontaneous plants, the Woodland crew has never planted this species. This is yet another species we have documented that highlights that urban parks are an important refuge for native plants.

Commonly called Spotted Wintergreen, or Spotted Pipsissewa, this perennial is native to eastern North America. It is a small plant, with leaves only 2-7 cm in length (1/2 - 2 1/2 inches) and 6-26 mm (an inch or less) in width.  The plant bears white flowers which sit atop a stalk. The flowers mature to a capsule and the seeds are dispersed by the wind. Wintergreen is also a common name used for plants in the Gaultheria genus, however, Gaultheria does not have the white stripe on the leaf and it has a bright red berry-like fruit.

Because botanists identify plants by their flowers and fruit, we don't normally make an herbarium specimen without flowers or fruit (called a sterile specimen). But this was a special find so Daniel made an herbarium specimen and DNA sample using just a few small leaves. 

Chimaphila maculata Ericaceae. Photo by Eric Whitaker

The final species I want to share with you today is a very interesting one and one that is not often seen in Central Park.  The last time I saw it was in 2009, although a handful of others have seen it more recently. We were hoping to find this for our project and thanks to Conservancy staff, we are able to include Monotropa uniflora  into our list. Alex Hodges of the Woodland staff tagged me in a photo and message via Facebook announcing that he had found a population in the Ramble along the Gill. Eric Whitaker also found a population up in the North Woods along the Loch.

A member of the Heath family, Indian Pipe, or Ghost Plant is native to temperate regions of European Russia, Asia, North America and South America. Its odd appearance is due to the fact that it lacks chlorophyll. Chlorophyll is necessary for photosynthesis, so without it, a plant needs another way to get energy. This species is a parasite - it steals resources from another organism, in this case a fungus. Monotropa is what is known as a myco-heterotroph.

Many plants have symbiotic relationships with fungi. These fungi live in the soil and connect to the plant's root system. The fungus can spread through the soil and absorb water and nutrients much more efficiently than the plant roots can. But fungi are heterotrophs - they need to ingest food in order to get energy to live. Plants are autotrophs - they harvest the energy of the sun and can make their own organic molecules, such as sugars and starches. Plants and fungi form what is called a mycorrhizal association with each other (myco meaning fungus and rhiza meaning root). The fungus helps the plant get enough water and nutrients and in return, the plant shares the sugars and starches it produces with the fungus.  The Monotropa parasitizes the fungus. It steals the starches and sugars and does not photosynthesize at all. Interestingly, the Monotropa specimen which is pure white in life, turns completely black on drying. Nothing can be done to preserve the white color.

Monotropa uniflora Ericaceae. Photo by Eric Whitaker.

Another invaluable collaborator has been Ken Chaya. Ken and his colleague Ned Barnard created the beautiful and informative map of all the trees in Central Park. Ken often accompanies Daniel and me on our forays into the Park and is able to provide us with locations and information on many interesting tree species. One of the difficulties with the tree species is trying to determine if the individuals are spontaneous or planted. Among others, Ken helped us add wild Betula lenta (Sweet Birch) from Huddlestone Arch in the North Woods to our list and we will soon be adding additional Carya (Hickory) species thanks to him. 

We updated the "wanted" list and recently redistributed it. We again got a flurry of emails with sighting of plants we are looking for. You can find the list here on our project website. It is exciting not only to have such a great group of people working with us, but to know that these interesting species are persisting and even thriving in the most heavily used park in the world. 

Scavenger Hunt

Daniel and I are into our third year of collecting for the Central Park Flora project. We have collaborated with many people and that has truly been one of the best parts of the project. Together, we have found many species and shared good times. We have taught and we have learned. We still have a ways to go to finish this project and we are reaching out for some help. 

The inspiration that led Daniel and me to embark on this project was the 2013 BioBlitz in Central Park and the paper* published in the Journal of the Torrey Botanical Society in 2007 that documents a previous floral inventory. Documenting the flora of an area every 10 years is good way to monitor what species are there and how their composition changes over time.

We are endeavoring to find each of the species on the 2007 list. Some may not be in the Park anymore, which is inevitable as all floras are dynamic. But we need to do our best to relocate as many species as possible from old lists.

This is where you all come in. Below is a table of species from the 2007 list that we have not yet documented. We included time of year and location seen, when that information was available from Bob's collection labels. We are asking if anyone sees these species in Central Park (or, in fact, any species you think might interest us!), to please contact us so we can document it. It is a botanical scavenger hunt! 


Family Name Scientific Name Common Name Last Seen Location Seen Date
Adoxaceae Viburnum opulus European Cranberrybush 05/23/2007
Amaranthaceae Dysphania botrys Sticky Goosefoot
Asteraceae Bidens connata Purplestem Beggarticks Harlem Meer, West Side 08/09/2007
Asteraceae Hypochaeris radicata Cat's ear
Asteraceae Lactuca biennis Tall Blue Lettuce West Drive at 101st Street 08/07/2007
Asteraceae Solidago juncea Early Goldenrod Reservior, southeast 06/29/2007
Asteraceae Solidago sempervirens Seaside Goldenrod
Asteraceae Symphiotrichum lateriflorum Calico Aster
Asteraceae Symphiotrichum pilosus Hairy Aster 09/25/2007
Brassicaceae Brassica rapa Field Mustard Pool, West Side 05/24/2007
Brassicaceae Hesperis matronalis Dame's Rocket Delacorte, behind, Opposite Island 05/17/2007
Brassicaceae Lepidium didymum Lesser Swine-cress West Drive 06/14/2007
Brassicaceae Raphanus raphanistrum Wild Radish 06/19/2007
Brassicaceae Sinapis arvensis Wild Mustard
Campanulaceae Lobelia inflata Indian Tobacco East Drive at 72nd Street 07/03/2007
Cannabaceae Humulus lupulus Common Hop
Caryophyllaceae Stellaria graminea Common Starwort North Meadow, West Side 06/15/2007
Cyperaceae Carex annectens Yellowfruit Sedge
Cyperaceae Carex radiata Eastern star Sedge
Cyperaceae Schoenoplectus americanus Chairmaker's Bulrush 05/31/2007
Equisetaceae Equisetum arvense Common Horsetail
Fabaceae Medicago sativa Alfalfa Turtle Pond and NW of North Meadow ball fields 06/15/2007
Fabaceae Vicia sativa Common Vetch Turtle Pond 05/04/2007
Fabaceae Vicia tetrasperma Smooth Vetch Turtle Pond 06/14/2007
Geraniaceae Geranium pusillum Small-flowered Crane's-bill 05/30/2007
Iridaceae Sisyrinchium angustifolium Narrow-leaf Blue-eyed Grass Ramble 06/29/2007
Juglandaceae Carya glabra Pignut Hickory
Juncaceae Juncus effusus Soft Rush
Lamiaceae Ajuga genevensis Upright Bugle Ramble 04/18/2007
Monotropaceae Monotropa uniflora Indian Pipe
Onagraceae Oenothera glazioviana Large-flowered Evening-primrose
Poaceae Bromus sterilis Poverty Brome
Poaceae Digitaria ciliaris Southern Crabgrass Delacorte 07/14/2007
Poaceae Holcus lanatus Common Velvet Grass North Meadow ball fields 06/21/2007
Polygonaceae Fagopyrum esculentum Buckwheat Wagner Cove 06/12/2007
Primulaceae Anagallis arvensis Scarlet Pimpernel Yard 06/19/2007
Ranunculaceae Anemone virginiana Tall Anemone Belvedere Castle, foot of stairs 07/10/2007
Ranunculaceae Ranunculus sceleratus Celery-leaved Buttercup Harlem Meer 08/05/2007
Rosaceae Fragaria vesca Woodland Strawberry Turtle Pond, north side 05/03/2007
Rosaceae Prunus x yedoensis Yoshino Cherry
Scrophulariaceae Penstemon hirsutus Hairy Beard-tongue
Urticaceae Urtica dioica Stinging Nettle Turtle Pond, North Side 06/01/2007

*The Naturally Occurring Historical and Extant Flora of Central Park, New York City, New York 1857-2007

Robert DeCandido, Neil Calvanese, Regina V. Alvarez, Matthew I. Brown and Tina M. Nelson
The Journal of the Torrey Botanical Society

Vol. 134, No. 4 (Oct. - Dec., 2007), pp. 552-569The Naturally Occurring Historical and Extant Flora of Central Park, New York City, New York 1857-2007

Meet the mustards!

Last year I had the pleasure to participate in the Van Cortlandt Park BioBlitz along side Richard Abbott, a wonderful botanist from the New York Botanical Garden. During his introduction to the students, he spoke about two different ways to approach plant identification. He called the first "imprinting". You learn the identification of plants by some means - someone tells you what it is or perhaps you look it up in a field guide. You learn that species. You do the same for each species you meet. This is how I started learning plant ID. It works, but there is a much better way. He explained the benefits of the second method -  learning the characteristics of plant families. If you learn one plant at a time (the imprinting method), each time you go into the field and meet a new plant, you have no foundation from where to begin your identification process. If you learn characteristics of families, you can immediately start narrowing down your choices and arrive at an identification much more quickly. For the next few blog entries, I thought I would begin sharing with you some family characteristics, focusing on species Daniel and I have collected for the project.

Today, let's start with the mustards, Brassicaceae. Many mustards bloom in the early spring, with some of them continuing through spring and summer. Brassicaceae is the family from which we get not only mustard, but a whole group of vegetables including cabbage, broccoli, cauliflower, brussels sprouts, kale, turnips and canola oil. But today we are focusing on the species you find growing wild in Central Park. 

This family is made up of mostly herbaceous species. The few woody species that exist are not from this part of the world. These herbaceous plants are often weedy, living in disturbed areas. It is also a family that is mostly found in the temperate and colder zones of the Northern Hemisphere, with very few species in the tropics.

The flowers are generally four-petaled, have four sepals, six stamens (four tall and two short) and one pistil with two stigmas. The four petals are often in the shape of a cross which gives us the old family name, Cruciferae (cross-bearing). The flowers are small but found in inflorescences, some of which can be quite showy. They are usually terminal, that is, found at the end of the stem.

The fruit, a silique, is a dry seed pod that is divided into two chambers by a papery partition and the pod splits open on two sides. The pods come in different shapes and sizes. Whatever shape they are, they spiral around the stem. When the mature pods split open, there are generally two rows of seeds in each partition.

The leaves in this family are usually alternate, sometimes in a basal rosette (leaves in a circular arrangement close to the ground). The leaves usually have an odor when they are crushed. These odors come from "mustard oils", compounds that contain sulfur. They taste bitter but are usually not poisonous.

Many of these species are host plants for the cabbage white butterfly, that is, they are the food plant for the caterpillar of this species of butterfly. They also provide nectar for a host of other insects. 

The first example here is one of the most common species we have. It is a European species that is an invasive in our woodlands. Garlic mustard, Alliaria petiolata has a white, four-petaled flower, typical of the family. It is a biennial that produces seed pods very soon after flowering. It is an easy weed to remove, but if you are trying to get rid of this plant, you must pull it before it begins flowering to avoid spreading the seeds. If you crush the leaves, you will see where it gets its common name - it gives a strong fragrance of garlic. 


Alliaria petiolata Garlic mustard

Alliaria petiolata Garlic mustard

Arabidopsis thaliana is an annual and is the fruit fly of plant research - it has been used in countless genetic studies and was the first plant to have its entire genome sequenced. It is native to Eurasia and northwestern Africa. The first photo below shows the seeds pods ripening while the stalk is still flowering. In the second photo below, you can see the leaves are in the basal rosette formation, low to the ground with few leaves on the flower stalks. It has a four petaled white flower, much less showy than Alliaria petiolata. It is a considerably less robust-looking plant than garlic mustard!

Arabidopsis thaliana Mouseear cress

Arabidopsis thaliana Mouseear cress

Another white-flowering mustard with long narrow seed pods is Cardamine hirsuta, hairy bittercress. This Eurasian native continues to flower as seeds ripen and the seed pods ascend past the flowers, almost vertical, as you can see in the second photo below. Its leaves are in the basal rosette formation, but these are pinnately lobed with each leaflet being round with wavy margins. If you look closely at the first photo below (or better yet, at a live sample on one of your walks!), the petioles (leaf stalks) have a few coarse hairs, hence the scientific name of the plant- hirsute means hairy. The main stem is hairy toward the bottom and hairless above. 

Cardamine hirsuta Hairy bittercress with unopened flowers

Cardamine hirsuta Hairy bittercress, fruits

This next mustard has yellow flowers, Sisymbrium officinale, Hedge mustard. A European native, it is easily recognized by its branching pattern. It is a fairly large plant that branches abundantly, often at right angles to the main stems.  In the second photo below you can see the leaves are narrow and lobed. The flowers are small with four yellow petals and four green to yellow sepals. The seed pods are appressed against the stem and curve up at the tips. 

Sisymbrium officinale Hedge mustard

Sisymbrium officinale Hedge mustard

Sisymbrium officinale Hedge mustard

Virginia pepperweed (Lepidium virginicum) is an annual that produces flowers and fruit for most of the growing season. Unlike many of the other member of this family that are from Eurasia, it is native to most of North America. The tips of the stems have numerous white flowers and the seed pods can be seen spiraling along the stems. The common name refers to the fact that young leaves and mature seed pods have a peppery taste. The seed pod is round with a shallow notch at the apex. The stems are covered with short, fine, white hairs. This species begins blooming in spring, peaks in summer and can still be found blooming into the fall.

Lepidium virginicum Virginia pepperweed

Lepidium virginicum Virginia pepperweed

Another Eurasian species, Capsella bursa-pastoris,  has seed pods that, to me, look somewhat like little hearts spiraling around the stem. But in fact the scientific and common names refer to a shepherd's purse. This is a very common weed and I have always enjoyed the little fact that the fruits are named for a shepherd's purse, but Daniel recently gave me a bit more information on this topic: shepherds made their purses from sheep scrotums! I will leave you with that fun fact and move on to our next species!

Capsella bursa-pastoris Shepherd's purse

Capsella bursa-pastoris Shepherd's purse

Whitlow grass (Draba verna) is a tiny beauty that can be found in lawns, roadsides and other disturbed areas. A native of Eurasia, it has naturalized over North America. The seed pods are somewhat oblong and the leaves form a basal rosette. You have to squat close to the ground to appreciate this one, but it is worth it.

Draba verna Common whitlow grass

Draba verna Common whitlow grass

For our last species of this blog, let's look at a very showy plant. Lunaria annua not only has bright violet inflorescences, it has large interesting seed pods. The seed pods are oval (or moon-shaped, which is what lunaria means) and translucent, you can see the seeds inside. Some of the common names such as Money plant or Silver dollar plant refer to the fact that the seed pods look like silver coins. These are often used in flower arrangements. The species is from Europe but has naturalized in many areas. In Central Park, Daniel and I know this species from one area only, in the Ramble by the Still Hunt statue on the east drive. If you find any in another part of the park, be sure to let us know!

Lunaria annua Money plant

Lunaria annua Money plant

2016 Begins! Let's look at buds!

After a very long hiatus, the Central Park Flora Blog is back! 

Daniel and I have begun the 2016 collecting season and we are very excited about it. This year will be challenging. We have a wonderful collection so far, many common species and many not so common. This year, we will have to search very carefully for any species we have missed. But we are looking forward to the challenge.

Since the weather has not warmed up much and things are moving along slowly, I thought I'd start with a look at buds. An important structure for the plants and a good character we can use to identify species in winter. Looking at them closely reveals beauty that is often overlooked.

There are two types of buds - leaf buds (also called vegetative buds) and flower buds. Both are embryonic structures that give rise to either leaves or flowers. Buds on woody species have protective coverings called scales. Annuals and herbaceous perennials generally have naked buds. This post is looking at woody species. Flower buds develop and open at different times for different species. The ones we see now are early-blooming species. As spring and summer progresses, keep your eye out for flower buds that will open later in the season.

As we will see from these photos, buds are not only very beautiful, but they are unique to each species and serve and as a good identification character. There are so many to choose from. So here, in no particular order, is a sampling of what you can find in our parks at this time of year.

One of our first trees to flower each spring is the elm. The photo below shows the vegetative buds and the flowers of the American elm, Ulmus americana. I took this photograph too late to show you the flower buds, but aren't those flowers beautiful! The flowers will be fertilized and producing fruit before the leaves come out, as you can see in the second photograph (which I took last year). American elm seeds have hairs along the edges, distinguishing it from other elm species. The bud scales are reddish brown and darker along the margins. The terminal bud (the one at the tip of the stem) is angled at about 45 degrees.

Ulmus americana Ulmaceae

Ulmus americana Ulmaceae

The red oak, Quercus rubra, has a cluster of several buds at the tip of the stem. This is a feature common to all the oaks. Red oak has these lovely chestnut-brown buds, sharp-pointed with hairs along the margin of the scales. This is a common oak in Central Park as well as in other parks around the City.

Quercus rubra Fagaceae

Carya cordiformis, the bitternut hickory, is easily recognized in the winter by its buds. The bud scales are valvate, that is, they meet along their margins and do not overlap. The buds are sulphur-yellow. No other tree in our area has buds of this color. This seems to be the only hickory that is reproducing on its own in Central Park. In fact, it does very well and can be found throughout the woodlands. The seeds are bitter and the squirrels do not like them.

Carya cordiformis, Juglandaceae

I first spot Sassafras albidum in the winter by its green stems, one of the few species to have this feature. Examination of the buds will confirm the identification of this species.

Sassafras albidum Lauraceae

The flower bud in sassafras is distinctive from the vegetative bud. It is much more plump. The green scales are reddish towards the tip. The flower buds are the terminal buds and the vegetative buds are all lateral and much smaller. The sassafras is often found along woodland edges and in clearings where there is sufficient sunlight. When it leafs out, take a sniff, the leaves have a terrific fragrance!

Sassafras albidum Lauraceae, flower buds

Ginkgo biloba, the Maidenhair tree, has short stout axial shoots. These shoots have no internodes which make them very short. A node is the location where leaves or shoots emerge. Internodes are the spaces between two nodes. In the image below, you can see this year's bud - the structure that looks like a brown cap, made of overlapping scales. Beneath the bud is a ring of leaf scars, the half-moon shaped structure with two spots in it. Leaf scars are structures that remain where leaves used to be when they fell off in autumn. The two spots in this scar are called vascular bundle traces and show where vascular tissue, xylem and phloem, took water and nutrients into outhe leaves. The shape of the scar and the number and pattern of vascular bundles are unique to each species and are used in conjunction with buds to identify woody species in winter. You can see in the case of the Ginkgo, for each year, a ring of leaf scars is left and there is no space between them, they just pile one on top of another, no internodes. 

Ginkgo biloba Ginkgoaceae

Like the American elm, our native spicebush, Lindera benzoin produces its flowers before the leaves emerge. Small clusters of yellow flowers are out now and the tender, green and very fragrant leaves are only now emerging from the leaf buds. The flowers will eventually become the fruit, an oval drupe (stony pit surrounded by fleshy pulp). By September, the fruit will be a beautiful scarlet. Spicebush is an understory shrub of moist woods.

Lindera benzoin Lauraceae

Emerging simultaneously are the leaves and the flowers of this buckeye species, Aesculus sp. You can see the leaves, still bronze, emerging below the buds of the inflorescences (clusters of flowers). Buckeyes have been planted in Central Park in the last ten years. This one is probably red buckeye, Aesculus pavia. It's European cousin, the horsechestnut (Aesculus hippocastanum) is more common in the park and around the city.

Aesculus sp. Sapindaceae

The London Plane, Platanus x acerifolia also has the leaves and inflorescences emerging at the same time. The globose (spherical) structures are the not-yet-mature flowers. The male and female flowers look similar but are carried on separate peduncles (flower stems). If you are able to zoom in on this photo, take a look at the beautiful pubescence (hairs) on the young leaves and the bud scales.

Platanus x acerifolia Platanaceae

Speaking of pubescence, look at the stem and buds of Rhus typhina, the staghorn sumac; easily distinguished from the other sumacs by the dense velvety hairs on the stem and buds. The sumacs reproduce nicely in sunny edges of the woodlands and they give us fantastic fall color. Sumacs are in the same family as poison ivy, mangoes and cashews.

Rhus typhina Anacardiaceae

One more for the fuzzy collection, Amelanchier sp. Serviceberry is a wonderful early blooming native shrub. The flowers are fragrant and very beautiful, but don't forget to look at the other parts of the plant, they are just as beautiful in their own ways.

Amelanchier sp. Rosaceae

By this time, all the red maple flower buds are gone. This is a very early flowering tree for us, with spectacularly red buds. But fear not, you can still enjoy the color and beauty of the red maple since they are still in fruit! The first photo below is one I took last year of the flower buds. The second is a recent photo showing the double samaras forming on a red maple, with the stigmas still present. They are the smallest samaras of our maples and the only ones that are red. But don't wait too long to go and see them, they do not persist all season!

Acer rubrum Sapindaceae

Acer rubrum Sapindaceae