HEBERLING LAB

What plant is this?  Well, we don’t know exactly.  This undetermined specimen was collected on December 29, 1976 by Jeffrey McElroy in Ecuador.  The label suggests it is in the same plant genus as the papaya (Carica) but was not yet identified to species.  Specimens in the herbarium are arranged by plant family, then genus, then geography (where it was collected), and in nearly every genus, at the bottom of all these folders is a black colored folder labelled “indet.” that includes those specimens that have not yet been identified to species.  I’m not sure why they are called “indet.” rather than “undet.”, as “undetermined” would be more appropriate.  Of the over 525,000 specimens in the Carnegie Museum herbarium, about 2% (= 10,588 specimens), are not (yet) identified to species.
 
This specimen is likely a member of a species already known to science, but an expert has not yet identified this particular specimen yet.  However, many undetermined specimens may be undescribed (that is, new to science!).  The name and description of new species (alpha taxonomy) is a major purpose of herbaria.  A study in 2010 estimated that of the estimated 70,0000 species yet to be described, over HALF are lying in herbaria right now!  They also found that only 16% of new species descriptions were done within 5 years of specimen collection, and 25% of new species descriptions involved specimens that were more than 50 years old!
Study abstract here: http://www.pnas.org/content/107/51/22169.abstract
 
Taxonomy (branch of science on classification of organisms) is always changing.  Species names are changed, what was once thought to be one plant species or family is split into many, and what was thought to several species is lumped into one.  And with further information or upon review by experts in particular plant groups. specimens are determined to be a different species than what the original collector called it.  Annotation labels are added to specimens all the time – these labels revise the species listed on the original label.  A typical annotation label includes the revised species name and details, the name of the person making the annotation, and the date.
 
Some specimens can have many annotations, which nicely demonstrates the community culture of science as a process with constant revision as we learn more about the world around us.

 Image above:  European mistletoe specimen collected on Christmas Eve, 1883.
Image below: Close up image of specimen label that reads: "a. purchased at Pittsburg market."  It took me a while to decipher this handwriting.  Note that Pittsburgh's official spelling was "Pittsburg" until 1911.  The mistletoe was for sale for the holidays, likely imported from its native range in England.

Well, specimens don’t get much more festive than this!  This mistletoe specimen (Viscum album) was purchased at a Pittsburgh market on Christmas Eve 1883 by John A. Shafer, who would become the museum’s first botany curator 16 years later.  Mistletoes refer to many species in the genus Viscum, but traditionally referred to a species native to Europe, Viscum album.  European mistletoe has a deep rooted cultural history, dating back to as early as ancient Greece, is a part of many legends and stories through human history, and remains a well-known holiday decoration today.
 
Did you know that mistletoes are parasitic plants? Mistletoes grow on the branches of trees (especially oaks), with specialized roots (called “haustorium”) that penetrate the host tree to obtain water and nutrients.  Technically, most mistletoes are hemi-parasites, as they do have green leaves capable of photosynthesizing to some degree.  How do they germinate high up on the branches of trees?  They have evolved to produce berries which birds ingest, fly around, land on another branch, and poop a viable mistletoe seeds.  Without the assistance of birds, the seeds would likely just fall to the ground.
 
Mistletoes are native to the United States, too.  American mistletoe (Phoradendron leucarpum) is native to southeastern US states.  The species has been harvested and sold in the US in Christmas traditions, similar to European mistletoe. The specimen pictured below was collected in South Carolina in 1968, found attached to several oak species.
 

This isn’t your typical herbarium specimen (or is it?). It is a “type” specimen collected by A.H. Curtiss on December 15, 1903 on the Isle of Pines, Cuba.  A “type” specimen is a specimen that was used to formally describe the species as new to science.  Therefore, type specimens have very special scientific and cultural significance.  This species was named Acisanthera glandulifera in 1917 by Carnegie Museum curator of botany, Otto Jennings.  Jennings and others went on expeditions to Cuba in the early 1900s, and many specimens are now preserved at the Carnegie Museum. 
 
Type specimens serve as a verifiable record for future researchers to compare and verify a given species’ identity. There are many different categories of types.  In particular, this specimen is a “holotype,” meaning it is the sole designated specimen that describes the species. Current rules set forth by the botanical research community are that the species description much be published in a peer reviewed journal and must designate one single specimen as the holotype.  Because individuals can vary in their feature, other specimens can be referred to in the species description as well.  These specimens would be known as syntypes.  Similarly, a specimen which was said to be made from the same exact individual as the holotype is known as the isotype.  It is common practice for botanists to send duplicates of the holotype (aka "isotypes") to other museums to be a part of their collection. 
 
Taxonomy (the science of classifying organisms) is an ever-changing science, subject to revision as more research is done, especially at the molecular (DNA) level. What was once thought to be one species might actually be several, and what was thought to be several species might actually be one.  In addition to a species being recognized as new, some species simply change their names as a result of new evidence suggesting it should be being placed in a different genus (thereby changing its binomial scientific name).  It might seem unnecessary to go to the trouble to name species or have botanists argue over what is a species and what isn’t.  But taxonomy is very important for both our basic understanding of the tree of life, but also for biodiversity conservation.  If we don’t know what species are out there, we won’t be able to effectively conserve the world’s biodiversity.  After all, it is tough to protect a species you didn’t know it exists.
 
Another major reason for changes in species names is more due to nomenclature rules and dealing with synonyms.  A species may be independently described multiple times and many species have a complex nomenclatural history (that is, they have been called multiple scientific names by different people). Assigning one accepted scientific name to a species helps to ensure that scientists working on the same species are indeed referring to it as the same species.
 
You’ll notice many herbarium specimen labels have additional labels (annotation labels) to update the specimen’s identity as new information becomes known.  An annotation label can be seen in this specimen pictured here (specimen was first labelled as a different species name).  In fact, a recently published treatment of this genus (Guimaraes et al. 2017, Brittonia) suggests this species name should be Acisanthera erecta.
 
Although this specimen isn’t your average specimen, can you say it is a “typical” specimen? [insert laugh here]

Above/below: The original 1917 publication by Jennings describing this species.

Below: Many type specimens are now available online (CM’s specimens are currently available on https://plants.jstor.org/ ).   Pictured here are duplicate specimens of the holotype (isotypes) in other herbaria.  Below is one specimen from the New York Botanical Garden (NY) and another from the United States National Herbarium at the Smithsonian (US).   I was able to find these duplicate specimens in a matter of minutes --thanks to recent digitization efforts!

​Are you decking your halls with boughs of holly?  This specimen of American holly (Ilex opaca) was collected by M.L. Bomhard in Mandeville, Louisiana by on December 8, 1928.  The holly revered for its holiday cheer usually refers to a related European species, Ilex aquifolium. But there are native holly species in North America that are equally (if not more) cheerful.  Like most other hollies, American holly is dioecious, meaning it has male and female flowers on separate plants.  Only the female plants have the characteristic bright red berries we all know and love.  American holly stands out as one of the few broadleaved evergreen trees native to the Eastern US (i.e., has green leaves during winter that are not needles). This species is near the northern edge of its range in Pennsylvania and is more common in southern states.  It is listed in PA as a species of “special concern” due to its relative rarity.  

These Pennsylvania specimens shown above were collected sometime in December (exact day unknown):  White Pine (Pinus strobus) in Kittanning in 1926 and Scots Pine (or “Scotch Pine”; Pinus sylvestris) from cultivation in Avalon in 1902.  Both of these species are cultivated and used as decorative trees for the holidays. Many evergreen conifer species are cultivated in the US for decorative use during the holidays.  Needle length, softness, retention, color, and even scent vary by species or variety. Similarly, branching patterns and branch strength differs. Plus, some species grow faster and easier than others, which means some species are cheaper.
 
Did you know that Pennsylvania is one of the top states for Christmas tree farms?  In fact, southwestern PA’s very own Indiana County is known as the “Christmas Tree Capital of the World.”  According to the Indiana County Christmas Tree Growers’ Association, the title arose in 1956, when an estimated 700,000 trees were cut that year in the county. 

Believe it or not, there are no CM specimens from Indiana County collected in the month of December.  This isn't all that surprising, as most specimens aren't collected in the winter.
 
Before farms began cultivating trees for that purpose in the early 20th century, people just went to the woods to cut down their tree for the holidays.   Some of the earliest Christmas tree farms in the US started in Indiana County as early as 1918.  Many farms in the region turned their fields into Christmas tree farms as it became profitable. By 1960, more than 1 million trees were harvested per year in Indiana County alone.  The harvest in Pennsylvania has declined for several reasons, including increased popularity of artificial trees and consumer interest in Frasier fir trees (Abies fraseri; native to the Southern Appalachians and grows slower in PA than farms in North Carolina).  However, Pennsylvania is still among the top five states in terms of both number of working Christmas tree farms and trees harvested. According to the National Christmas Tree Association, 31,577 acres in Pennsylvania are used as Christmas tree plantations. Many of the Christmas tree lots in southwestern PA get their trees from farms in Indiana county.