A Rare and Diminutive Skullcap: Scutellaria leonardii

Scutellaria is a large genus, with 350+ species scattered all over the world.  One of the smallest and rarest of these is Scutellaria leonardii, which is found in only 5 counties in North Carolina, but is mostly confined to Durham and Granville Counties.  The common names Shale-barren Skullcap and Glade Skullcap help to describe some of its favored habitats.  It is also found on dry road banks where there is little competition from surrounding vegetation.

Below is a small population as it appears in early spring.  The plants are only a few inches tall at this time, with stubby, ovate leaves. It is growing out of a thin layer of dry, rocky soil, as can be seen in this photo at the base of the plants.

Scutellaria leonardii
Shale-barren Skullcap
Young plants

Below is a closer look at the leaves of a young plant, which are about one half inch long and attached directly to the stem.

Scutellaria leonardii
Shale-barren Skullcap
Leaves

As the plant grows, the upper stems produce leaves that are more elongated, with depressed vein patterns.  The leaves still never reach an inch in length.  The pink structures are the calyces, which protect the flower while it develops.  In S. leonardii, they are a striking pink color that can often help to find the tiny plants.

Scutellaria leonardii
Shale-barren Skullcap
Calyx and Leaves

Scutellaria is a member of the mint family, the Lamiaceae, which are known for having square stems.  The square stems of S. leonardii can be seen below.

Scutellaria leonardii
Shale-barren Skullcap
Square Stem

The tiny blue flowers can be seen below.  The lower petals have 4 lobes.  The front view shows the fine hairs along the top of the upper portion of the flower and the lobes.  The second photo gives a side view, where it is easier to see the overhanging “helmet” of the flower, from which the common name “skullcap” is derived.

Scutellaria leonardii
Shale-barren Skullcap
Flower – Front View

 

Scutellaria leonardii
Shale-barren Skullcap
Flower – Side View

All of the important structures of the plant can be seen illustrated in the photo below.  On the left, the flower buds can be seen as they are just developing, with the lower left showing the elongating bud just starting to open, and the open flower on the right.  The pink calyces at the bottom have lost their flowers and are becoming seed capsules.

Scutellaria leonardii
Shale-barren Skullcap
Plant Structures

Scutellaria leonardii is very rare in North Carolina: Status Endangered and Rank Imperiled.  It’s full, mature size is only 6 inches tall, making it tough to see and find, even for trained field botanists.  According to Vascular Plants of North Carolina (https://auth1.dpr.ncparks.gov/flora/plant_list.php), S. leonardii is declining in North Carolina for a host of reasons, not the least of which is encroaching vegetation.  Management of these rare populations thus emphasizes keeping the plants free of intrusion by surrounding weeds and vines.

Herb Amyx

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