Poisonous Umbellifers (Apiaceae, part 3)


Isn’t that pretty?

It’s also deadly.

Umbellifers can be tasty, and they can be poisonous. And they can be both. The deadliest plant in North America is a native umbellifer, and the notorious European native pictured here is widespread in the Maryland piedmont. This specimen was right on the Billy Goat C trail.


This is Conium maculatum, aka poison hemlock. It’s found throughout the US (except Mississippi and Florida) and most of southern Canada, and is on the noxious weed list in eight states. It likes moist soils in disturbed areas and can grow to eight feet tall in its second year (it’s a biennial). In young plants all you’ll see is a basal rosette of leaves.


Most of the brown material in the above photo is poison hemlock plants that are dead or dying after setting seed (there’s a still-flowering plant on the left side, but you have to zoom way in to see it).

There are five related alkaloids present in poison hemlock, but the one that occurs in greatest concentration is coniine, a peripheral nervous system disrupter. It doesn’t take much coniine to kill an adult human (The LD50  (mice) is in the range of 10 milligrams per kilogram of body weight). Remember that umbellifers often have hollow stems? There are documented instances of children dying after blowing across the tops of cut poison hemlock stems.

North America’s deadliest plant is Cicuta maculata, the spotted water-hemlock. It grows in wet areas all over the US and Canada, including the Maryland piedmont. The plant looks similar to Conium maculatum but usually the foliage is not as finely cut, and it doesn’t get quite as tall. Despite being a native it’s on the noxious weed list in Nevada. There are three other species of Cicuta native to North America; of these C. bulbifera, bulblet-bearing water hemlock, has been recorded in Montgomery and Cecil counties, but it is listed as Endangered/S1 (highly state rare). The poisonous compound in Cicuta species is called cicutoxin. It’s a central nervous system disrupter that usually causes death by respiratory failure. The LD50 (mice) is 2.8 mg/kg.

(By the way, the specific epithet “maculata” or “maculatum” means spotted.)

There are a few other species of umbellifers found in parts of the US that have similar toxicity, but none of those are found in Maryland.

For the most part the poisonous compounds found in umbellifers fall into two broad categories: systemic poisons and phototoxins. When a phototoxin – say the sap from an umbellifer – gets on the skin, nothing happens. Until the skin is exposed to sunlight. Then there is a reaction that renders the skin highly photosensitive, so that sun exposure causes burns. Second degree burns, even. And the resulting skin discoloration and scarring can last for months or be permanent.

Wondering which plants have phototoxic compounds? It’s an interesting list, and includes species in a number of families, including the citrus family. Depending on which authority you consult, most of the vegetable and spice umbellifers at least have the potential to cause such a reaction. This includes anise, carrots, celery, chervil, coriander, dill, fennel, lovage, parsley, and parsnip. Usually the reaction isn’t bad, but it’s a good idea to wear gloves and long sleeves when handling them in the garden.

Interestingly, the celery reaction only happens when the celery has been infected with a particular species of fungus.

Among the phototoxic umbellifers, none looms as large as the giant hogweed,  Heracleum mantegazzianum. I mean that both literally and figuratively. Literally, because this Caucasian native can grow to 18 feet tall. It’s a biennial, so that means it grows to 18 feet in a single season. And figuratively, because the sap is exceptionally dangerous. Crews in New York and British Columbia tasked with removing it suit up head to toe to prevent the sap from touching them. This video has a rather silly intro but basically good information. There’s a lot of good information on the New York State Department of Environmental Conservation website.

Giant hogweed is on the federal noxious weed list and on 13 state lists. It’s found in a handful of states in the Pacific northwest, upper Midwest, New England and mid-Atlantic, and North Carolina. The Maryland Biodiversity Project has records for it in Garret, Baltimore, and Harford counties.

Giant hogweed has two cousins present in the US, H. maximum (native) and H. sphondylium (alien), both of which are commonly called cow parsnip. The former is present in the Maryland piedmont, but there are no records of the latter in Maryland. Both species contain phototoxins, but are not nearly as dangerous as H. mantegazzianum.

next time: more flower pix

Tasty Umbellifers (Apiaceae, part 2)

Many umbelliferous plants are used as vegetables, herbs, and spices. Here’s a list.

But first, a note on terminology: although everyone refers to the spices as “seeds”, they’re actually fruit, specifically a type called schizocarp, a dry fruit that will split into segments, each of which contains one seed; plants in the Apiaceae always have schizocarps that split in two parts. In the text below I’m sticking with common usage and referring to them as seeds. But really they’re fruit.


Daucus carota   Although the carrot is a biennial plant, the roots are harvested during the first year of growth. The plant is native to Eurasia, but found in the wild in all the lower 48 states and much of Canada; as wildflowers, they’re called Queen Anne’s lace, and on noxious weed lists in Iowa, Michigan, Ohio, and Washington. Older sources sometimes refer to two subspecies, D. carota ssp. sativus and D. carota ssp. carota; these names are now considered obsolete by ITIS.


Pastinaca sativa   Like the carrot, the parsnip is a biennial plant whose roots are harvested during the first year. Also native to Eurasia and now established in North America except in the Deep South. Parsnip is a prohibited noxious weed in Ohio.


Apium graveolens  The stalks, leaves, and seeds of celery are used. The plant is a biennial native to central and southern Europe, southwestern Asia and North Africa. Probably. Celery has been cultivated for so long there’s a lot of confusion about its origins. It’s become established in parts of the US, in an arc running from New York south, west, and then north into Washington. The variety A. graveolens var. rapaceum is grown for the root, called celeriac.

Perideridia  There are 13 species in this genus, all with the common name yampah. It’s a perennial plant native to western North America. The roots were an important food source for Native Americans.

Arracacia xanthorrhiza   Arracacha is a perennial native to the Andes, grown for the edible root.

Foeniculum vulgare   Sometimes incorrectly labeled anise, fennel is a perennial grown for the swollen stalks at the base of the plant (the “bulb”). It’s native to the Mediterranean but has naturalized in much of Europe and in the warmer parts of the US. Fennel is on the California Invasive Plant Council’s Invasive Plant Inventory for moderate invasiveness and severe impact (2006 version).

Levisticum officinale  The native range of lovage is uncertain; probably Europe or Asia. It’s a perennial and once established can be hard to get rid of. Both the stalks and leaves can be eaten. The flavor is intense, like some sort of super-celery. A little goes a long, long way.

Anthriscus cerefolium (sometimes spelled cereifolium) This southern European native is an annual plant that deserves more respect. Chervil is used mostly in French cuisine, in delicate dishes because the flavor is mild. Although the leaves are sold in dried form, don’t bother buying them; the volatile oils are lost during drying and the result is flavorless. Chervil is trivially easy to grow from seed.

Petroselinum crispum   Parsley is a biennial generally used as an annual, since the leaves can get harsh or bitter in their second season. There are scattered populations established in parts of the US, but it’s not listed anywhere as a weed. It’s native range is uncertain, possibly the Levant or nearby areas.

Anethum graveolens   Dill is annual, naturalized in much of the US and Canada but native to Asia minor and the Mediterranean. Both leaves and seeds are used. The common name “dill weed” is a clue that this plant is really easy to grow.

Carum carvi   Caraway is an established alien in Canada and the northern half of the US (more or less), and a B-list noxious weed in Colorado. It’s a biennial native to Eurasia and north Africa. Caraway seed is familiar as the dominant flavor in rye bread and aquavit.

Pimpinella anisum   I blame Alton Brown (of Good Eats fame) for the increasingly widespread mispronunciation of the word “anise”. It’s pronounced ANis, not anEECE (google it). The plant is an annual native to southeastern Europe and southwestern Asia. My Italian forebears would roll in their graves if I used anything other than anise seed to flavor pizzelles.

Myrrhis odorata   Both the leaves and seeds of cicely are used as a flavoring, though the use is not widespread. The plant is a perennial native to south-central Europe, with scattered naturalized populations in the US and Canada.

Coriandrum sativum   Called cilantro for the leaves, shoots, and roots, and coriander for the seed, this annual is native to southeastern Europe, southwestern Asia, and north Africa. It’s present in parts of North America but not listed as a weed by any authorities.

Eryngium foetidum  Grown for the leaves, culantro (often confused with cilantro) is used in Southeast Asia, the Caribbean, and Central America. It also grows in Georgia and Florida. I can’t find any authoritative information about its native range, but it is a tropical annual.

Cuminum cyminum   Cumin is an annual plant native to the eastern Mediterranean and central Asia. The seeds are used in many cuisines around the world.

Bunium bulbocastanum   The seeds of this perennial plant are known as black cumin, black caraway, and kala jeera. It’s native to southeastern Europe and south Asia.

Trachyspermum ammi   Ajwain is an annual native to south Asia, grown for the seeds.

Ferula assa-foetida   The dried and ground sap or resin of the roots of this perennial is called asafoetida. The powder is used sparingly in various Indian cuisines, more as a flavor enhancer than a flavor in itself. The plant is native to western Asia.


now my kitchen smells like an Indian restaurant

Many umbelliferous plants contain poisons of various sorts, including some of the plants described above. More on that next time.

Foods, Flavorings, and Poisons: Plants of the Apiaceae (part 1)

The Apiaceae, also known as Umbelliferae, is the 16th largest plant family in the world (1), with almost 3,800 species in over 300 genera (2). Plants in this family are found almost everywhere (except Antarctica), but mainly in northern hemisphere temperate regions and tropical highlands. Within the US, the Apiaceae is the 11th largest family, with 349 (native) species.

Sixty-five species of umbellifers can be found in the state of Maryland, though 28 of these are non-native, and many of those are waifs (plants that are alien and known to be present, but not in established populations). Of the 65, maybe half are present in the piedmont.

Umbellifers are usually herbaceous and can be annual, biennial, or perennial. Although identifying individual species can be difficult, as a family they are easy to recognize. There are always exceptions, but general characteristics to help you identify them include:

  • hollow stems (between the nodes)
  • sheathing at the nodes
  • compound or twice-compound pinnate or palmate leaves, arranged alternately
  • aromatic foliage
  • seeds enclosed in schizocarps (a dry, often woody fruit)
  • tiny flowers arranged in umbels or more often compound umbels


This last characteristic is the one from which the older family name is taken. An umbel is an arrangement like an umbrella, with pedicels (individual flower stalks) all growing from the same point. In a compound umbel, multiple secondary peduncles originate from one point and terminate in individual umbels, with pedicels and flowers arising from these.


Few plant families have such easily identifiable inflorescences, but be careful: getting the details right can mean the difference between life and death. Literally. More in the next few posts.

(1) Wikipedia
(2) Stevens, P. F. (2001 onwards). Angiosperm Phylogeny Website. Version 12, July 2012 [and more or less continuously updated since] (Missouri Botanical Garden)

Brain Fruit


One day in October I was looking for parking in a residential area in Washington, DC. When I found a stretch about a quarter block long that was devoid of cars, two thoughts went through my mind in quick succession: “hooray!” and “wait, this is too good to be true.”

It was too good to be true, not because of DC’s often byzantine parking restrictions, but because of the large number of softball-sized green things on the street: brain fruits, also known as hedge apples, horse apples, monkey balls, mock oranges, and osage oranges. Those things falling off a tree can put a heck of a dent in a car.



autumn leaves and characteristic deeply furrowed bark




These fruits come from the tree Maclura pomifera, which goes by many common names, including the ones above (except brain fruit and monkey balls), yellow-wood, and bodark, a corruption of the French name bois d’arc (bow-wood). It’s in the mulberry family (Moraceae), which also includes fig (Ficus carica), jackfruit (Artocarpus heterophyllus), and breadfruit (Artocarpus altilus). Jackfruits are thought to be the largest tree-fruit in the world (they can weigh up to 80 pounds), and breadfruit saplings were the precious cargo on the HMS Bounty when the crew mutinied.

The native range of the osage orange is thought to be Arkansas, Oklahoma, and Texas, primarily in the Red River basin. However, it can be found across much of North America because 1. it was extensively planted for hedgerows and windbreaks, and 2. as a pioneer species it can be agressive or even weedy. But it was incredibly useful, with highly rot-resistant wood that made great fence posts as well as bows and tool handles. And it’s thorny, so planted close together and pruned to keep it short and dense it made effective livestock fencing: “horse high, bull strong and hog tight”, as the saying went.*



leaf and fruit; this leaf blade measured 6.5″, and the petiole another 2.5″;
the fruit was 3.5″ in diameter



The tree can grow to a height of 65 feet, but is often somewhat shorter. It’s dioecious, meaning that plants bear either male or female flowers. Despite having a specimen almost in my backyard, I’ve never seen the flowers, which are generally described as “inconspicuous”.

But I see plenty of brain fruits.

One time a few years ago a big storm knocked a large, mostly dead branch off the tree and into my yard. I was happy to collect the wood, cut it, and season it, because osage orange wood has ridiculously high BTU value.








*I spent a long time trying to find the origin of this phrase. The earliest use I could find was as a description of a “lawful” fence (osage orange or not), in an 1878 newspaper article in Sherill’s History of Lincoln County, North Carolina:

The question of no fence law was agitated. Up to this time cattle and hogs had free range and field crops had to be fenced in. A lawful fence was “horse high, bull strong and hog tight.”

The Aster Family (part 5): Odds and Ends

Did you know that there’s a word for the study of the Asteraceae? It’s synantherology. And, a person who studies the Asteraceae is a synantherologist.

I was going to write a post about the lower orders of classification within the aster family. But it ends up being unusually complicated, with various authors positing sub-families, super-tribes, tribes, sub-tribes, and even sub-genera as ranks between family and species. If you’re really interested, check out the Asteraceae page at the Tree of Life Web Project, or Classification of Compositae from the International Compositae Alliance.

So rather than another detour into taxonomy, here’s a gallery of aster family oddballs: flowers that might not look like composites at first glance.


Anaphalis margaritacea
pearly everlasting

Maryland Biodiversity Project has only 2 records for this plant, including one in the piedmont, so it’s unlikely you’ll see it in this area. But you’ll see it often in floral arrangements. The yellow-ish centers are the disk florets, and the white outer parts are bracts; there are no ray florets.20140915-DSC_0024


Antennaria plantaginifolia
plantain-leaved pussytoes

This plant is found throughout the Maryland piedmont. White disk florets only, surrounded by green phyllaries. Look at those little seeds!


Elephantopus carolinianus
Carolina elephant’s foot

Found throughout the Maryland piedmont. Click on the image and then zoom in to see the details: this head is showing four individual disk florets, each with a five-lobed corolla. There are no ray florets.




Erechtites hieraciifolius var. hieraciifolius
pilewort; fireweed; burnweed

Found throughout the Maryland piedmont. My apologies for not having a clearer picture. The flower heads contain disk florets only (no ray florets).


Conoclinium coelestinum
blue mistflower
(with eastern tailed-blue butterfly)

Found throughout the Maryland piedmont. Disk florets only.




Eutrochium purpureum
sweet joe-pye weed
(with eastern swallowtail butterfly)

Found in most of the Maryland piedmont.  Disk florets only.