HEBERLING LAB

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Not all plants in our area photosynthesize!  Collected on September 29, 2007, this specimen was collected by Loree Speedy in dry woods in Burrell Township, Indiana County, PA (near Blairsville).  Often mistaken for a fungus, Monotropa uniflora, commonly known as the “ghost plant” or “Indian pipe,” is indeed a flowering plant in the blueberry family (Ericaceae).  When alive, the plant is white (hence the name “ghost plant”), but turns black when dried. It lacks the green chlorophyll pigments of most plants, and therefore does not make its own sugars through photosynthesis.  Instead, Indian pipe is a heterotroph.  Like humans, heterotrophs ingest or absorb carbon necessary for life from organic sources, rather than fixing carbon from atmospheric carbon dioxide through photosynthesis).  More specifically, this plant is a myco-heterotroph.  The way this plant gets its food is incredible.  It parasitizes mycorrhizal fungi in the soil.  And where does the mycorrhizal fungi get its food? These fungi form a close relationship (symbiosis) with many forest trees, shrubs and herbs, where the fungi aid the host plant in water and nutrient uptake and the fungi receive sugars from the plant in return.  This complex relationship was shown using radioactive carbon dioxide, tracking “tagged” carbon molecules from a host tree to Indian pipe. So…ultimately, the food for this non-photosynthetic plant comes from other plants in the forest!

North America used to have over 150 species in the genus, Aster.  But now only one species remains.  That isn’t because they went extinct, but instead, they were re-named.  Many of these species are still referred in general as “asters.”  Collected on September 22, 1900, this specimen was found in Fern Hollow, Frick Park, Pittsburgh by early museum botanist John Shafer. Eurybia divaricata (formerly Aster divaricatus) is commonly known as “white wood aster.”  This beautiful fall blooming plant (like many asters) is a common native in eastern US forests.  So why the new name?  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.  As we understand how organisms are related, we can better understand the history of life on earth.  Taxonomic studies of plants often lead to splitting of one species into many or the lumping of many species into one. In some cases, a “new” rare species may be have been hiding under our noses, previously grouped with another species. These studies are important for the conservation and protection of vulnerable species. We must know what these species are to actually protect them!
 
Like most herbaria (plural for herbarium), the Carnegie Museum herbarium is organized by genus within families.  Earlier this year, collections manager Bonnie Isaac and a team of interns and volunteers reorganized the sunflower family (Asteraceae), one of the largest families of flowering plants.  After a month of reorganizing and renaming folders, the work is still ongoing.  No surprise, as this family is represented by over 51,000 specimens (or about 10% of the entire collection)!  Ongoing taxonomic rearrangements like these are just one reason why the work of herbarium staff is never done.

​It is that time of year when old fields across western PA are painted yellow.  Collected on September 15, 1946, this specimen was found in New Baltimore, Somerset county, PA by an influential Curator of Botany at the museum, Otto Jennings. There are many species of goldenrod (in the genus Solidago) in our region.  They are often associated with runny noses and sneezing from fall allergies (hay fever), but don’t blame the goldenrods! Their relatively heavy pollen rarely becomes air-borne, but rather these plants are insect-pollinated.  Wind-pollinated species, like ragweed, are more likely your culprit.
 
This specimen pictured here (split between two herbarium sheets) is Canada goldenrod (Solidago canadensis).  Canada goldenrod is a fall blooming native species common throughout western PA.  However, it was introduced to Europe and Asia for use in floral arrangements and gardens, and has since become an invasive weed in other parts of the world.

​Collected on September 8, 1991, this specimen was found near Tarentum, PA by Walt Zanol.  If you had to pick the most aggressive invasive plant in the Pittsburgh area, knotweed would be among the top choices.  This particular specimen is Bohemian knotweed (Fallopia xbohemica), a hybrid between giant knotweed (Fallopia sachalinensis) and Japanese knotweed (Fallopia japonica).  Japanese knotweed was introduced from East Asia and Giant knotweed came from Sakhalin (Russia).  The hybrid likely originated when these two species “met” after they were introduced in Europe.  Both species and their hybrid can be found around Pittsburgh, often in enormous dense clusters along highways and waterways.  Take note on your drive to work or walk in the neighborhood – knotweeds are all around! 
 
Giant knotweed is distinguished by its large (usually much larger than your hand), heart-shaped leaves.  Japanese knotweed and the hybrid Bohemian knotweed are much more difficult to distinguish, with much variation in leaf shape.  In fact, the hybrid was only recognized in the early 1980s and was largely overlooked in the US until even more recently.  Some suggest it invades more aggressively than its parents. Most specimens in the Carnegie Museum of Natural History’s herbarium were originally identified as Japanese knotweed.  Last year, Allison Cusick, Research Associate in Botany at the museum, went through all 212 knotweed specimens and reidentified many as the hybrid.  In fact, only 3 of the specimens from Allegheny county were identified as Japanese knotweed!

For more info, see Zika & Jacobson (2003) Rhodora 105:143-152. https://www.jstor.org/stable/23313523?seq=1#page_scan_tab_contents

All three knotweeds collected a couple weeks ago at the same site near the Allegheny River and Barking Slopes Conservation Area, New Kensington/Plum, PA.  Left to right: Japanese knotweed (Fallopia japonica), Bohemian knotweed (Fallopia xbohemica), Giant knotweed (Fallopia sachalinensis).