HEBERLING LAB

Has your Charlie Brown tree lost its needles yet?
 
Not all needled-leaved trees are evergreen! Yes, there are deciduous species in the Pine family (Pinaceae).  That is, unlike most needle-leaved trees that retain their leaves all year long (evergreen), there are several conifer species that shed their leaves each year for the winter. Perhaps most famous are a group of species called larches.
 
No, this needle-free specimen of twigs and a cone wasn’t collected by Charlie Brown on Christmas Eve. Rather, this humble yet festive specimen of European larch (Larix decidua) was collected by J.F. Lewis on December 24, 1934.  Native to the mountains of central Europe, this species was planted in a cemetery in Northumberland county (central Pennsylvania).  It is highly likely the tree is still there – many decades later – as European larches can live for many hundreds of years (perhaps even a thousand years!). 
 
The herbarium at California University of Pennsylvania is named the person who collected this specimen – John Franklin Lewis.
 
European larch recently made the big time news too, featured in a new study published in the scientific journal Science.  The researchers used leaf out and leaf fall data collected from across Europe since the late 1940s for four tree species (including European larch). Surprisingly they found that trees may drop their leaves much earlier than expected with ongoing climate change.  In other words, as spring temperatures warm, deciduous trees produce leaves earlier in the spring, but this also causes trees to drop their leaves earlier in the fall.  This means that climate change may not result in longer growing seasons, as has been previously predicted.  You can read more about this study here: https://crowtherlab.pageflow.io/phenology-autumn-senescence#276245
 
 
Find this Charlie Brown larch specimen (and more) here: https://midatlanticherbaria.org/portal/collections/list.php?db=all&catnum=CM228058&includeothercatnum=1

This specimen of eastern hemlock (Tsuga canadensis) was collected by former Carnegie Museum botany curator Sue Thompson on November 3, 1984 in Somerset County.  Not only was this specimen collected in the highest point in Pennsylvania (Mt. Davis, 3,213 ft), but the species is also the official state tree of Pennsylvania.  How’s that for your state trivia!?! 
 
And this is a nice-looking specimen! Hemlock is a challenging species for the herbarium.  It is notorious for shedding all of its needles when dried.  Many specimens are just sticks with all the fallen needles shoved into an envelope.
 
Eastern hemlock (Tsuga canadensis) is a culturally and biologically important species.  A keystone dominant species found across many eastern North American forests, hemlock serves as important habitat to many birds, among other species.  Its leaves are evergreen and remarkable in casting some of the deepest shade, making the understory below it distinct.  Many species are adapted to “hemlock-hardwood forests.”  It provides food, shelter, and impacts nutrient and water cycles.  It is a late-successional tree, meaning its presence often indicates older, more intact forests.
 
Unfortunately, this species is in decline across its range, and it may become the “next American chestnut” so to speak.  Hemlock is attacked by an introduced, invasive insect – the hemlock wooly adelgid (Adelges tsugae).  The sap-sucking bug was accidentally introduced from its native East Asia, spreading to eastern hemlocks in the 1950s. First in the southern US, the impacts of the adelgid are clear in Great Smokey National Park, with hemlock stands wiped out and only the dead trunks and branches.  The insect is fairly new to western Pennsylvania, only found in our region relatively recently and not yet fully spread.  Check the undersides of hemlock needles for hemlock wooly adelgid.  If tree is infected, you’ll see their distinctive white cotton-like egg sacs.
 
As forest pests like the hemlock wooly adelgid spread and affect our forests, herbarium specimens are critical, serving as baseline data for species distributions and effects on other species through time and across sites.
 
Find this specimen online here: http://midatlanticherbaria.org/portal/collections/individual/index.php?occid=11739325 

 
Around 25-30 million cut trees are sold each year in the United States for the holidays. The popularity of certain species for this use has changed through time.  Many different 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 characteristics and branch strength differs by species. Plus, some species grow faster and easier than others, which means some species are cheaper.
 
This specimen of Fraser fir (Abies fraseri) was collected in Philadelphia at the Thomas Meehan & Sons Nursery.  The person who collected this specimen and the date of collection are unknown.  Thomas Meehan immigrated to the United States from England in 1848 and started a landscaping business.  With his three sons, he started the Thomas Meehan & Sons Nursuries in 1896.  The nursery was unique in that it specialized in native trees and shrubs, unlike most nurseries that focused on European and Asian varieties (still very common today).  The nursery closed in 1916.
 
Fraser fir is currently one of the most popular Christmas trees.  It is known for its dark green color, soft needles, stiff branches (great for hanging heavy ornaments), and has good needle retention.  Unfortunately, native to the Southern Appalachians, Fraser fir isn’t the easiest to grow in Pennsylvania.
 
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, PA 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 (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.
 
This specimen image is now online and publicly available here:
http://midatlanticherbaria.org/portal/collections/individual/index.php?occid=11736894&clid=0
 

In honor of the cool, new Tropical Forest Cuba that opened yesterday at Phipps Conservatory and Botanical Gardens, here’s a specimen collected in Cuba 115 years ago today.  This pine specimen of Pinus elliottii, known as slash pine or Cuban pine, was collected by George Russell Shaw in the Isles of Pines, Cuba (now known as Isla de la Juventud).  Shaw was an influential botanist working at the Arnold Arboretum (Harvard) who specialized in pines.   
 
The Carnegie Museum of Natural History has many specimens from Cuba.  Curator of Botany Otto Jennings and others went on expeditions to Cuba in the early 1900s, and many specimens are now preserved at the Carnegie Museum and elsewhere.  The Carnegie Museum herbarium includes 4,068 specimens from Cuba, of which 54 are type specimens (meaning they are associated with the description of a species new to science). 
 
Learn more about the plants and culture of Cuba at Tropical Forest Cuba at Phipps Conservatory and Botanical Gardens!

Above: Publication resulting from expeditions to the Isles of Pines, written by one the first curators of botany Otto Jennings, who researched the plants of Cuba. 631 specimens from Cuba collected by Jennings reside in the Carnegie Museum herbarium today. 

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.