June 21: 112, 85, and 59 years ago!

Whoa, this plant will catch your attention!  Although towering in at up to 8 feet tall with leaves 2 feet wide, Cow parsnip (Heracleum maximum, aka Heracleum lanatum) is not a tree, but herbaceous (non-woody). This species is the largest member of the carrot family (Apiaceae) native to North America. It can be found along shaded roadsides, waterways, and edge of woods. Its flower structure consists of many small white flowers on short stalks connected at a single point – an umbrella of flowers - botanically known as an “umbel.” Umbels are characteristic of the carrot family (think of the perhaps better recognized Queen Anne’s lace, Daucus carota, which is also known as “wild carrot”).
 
These specimens were all collected on June 21– but years apart - on 1907 (Westmoreland county, PA), 1934 (Pittsburgh), and 1960 (Beaver county, PA).   
 
This species is often confused with giant hogweed. Cow parsnip is often confused for the non-native plant called giant hogweed (Heracleum mantegazzianum). Giant hogweed has hit the news media in past few years and on many people’s radar, as it is considered a significant public human health concern. This plant is highly poisonous and designated as a federal noxious weed.  The sap of giant hogweed causes “phytophotodermatitis,” meaning serious skin inflammation occurs when contacted skin is exposed to sunlight.  Skin rashes can be very severe.  The sap can cause temporary or permanent blindness. Cow parsnip has a similar set of chemicals in its sap, and although not as poisonous, be  careful around these plants.
 
Giant hogweed can be 8-20 feet tall with leaves up to 5 feet wide!  It is thought to be eradicated in Pennsylvania. Although similar to the Pennsylvania native species cow parsnip, giant hogweed is noticeably larger in height and flower size. (see herbarium specimen here – it took 6 sheets!)
 
See here for a nice comparison between these similar species. https://www.maine.gov/dacf/php/horticulture/hogweedlookalikes.shtml
 
Given the size of members of the genus, the name Heracleum (derivative of Hercules) is quite fitting.
 
Specimen records and images for this species in the CM herbarium are now publicly available online:
http://midatlanticherbaria.org/portal/collections/list.php?db=328&taxa=Heracleum+lanatum&usethes=1&taxontype=2