Portulaca smallii (Small’s Purslane) at the Mitchell Mill State Natural Area

Portulaca smallii (Small’s Purslane) is a rare, protected plant, endemic to the thin soils of granite flatrocks and outcrops in the Piedmont regions of Virginia, North Carolina, South Carolina (a single site) and Georgia.  The Mitchell Mill State Natural Area contains the largest granitic flatrock community in North Carolina, and Portulaca smallii is present there, scattered through much of the flatrocks.   At Mitchell Mill, P. smallii  is found only in a restricted zone, in thin soil between the open rock and the deeper soils and background vegetation behind it.   In other sites, it has been reported to colonize nearby fields and disturbed areas, but this has not been seen at Mitchell Mill.

P. smallii is a succulent summer annual, a member of the large Purslane family, the Portulacaceae.  The photo below is of an aggregation of plants as they would appear to a passer by.  Notice the close proximity to the exposed rock and the thinness of the soil.

Portulaca smallii Small's Purslane Collection of Plants

Portulaca smallii
Small’s Purslane
Collection of Plants

Closer views of individual plants are illustrated below.

Portulaca smallii Small's Purslane Plant Form

Portulaca smallii
Small’s Purslane
Plant Form

Portulaca smallii Small's Purslane Closer View

Portulaca smallii
Small’s Purslane
Closer View

The seeds of P. smallii primarily germinate in spring and early summer, and flowering often follows closely in a month or so.  The flowers are usually a pale pink, and can be so pale as to appear white at times.  The flowers open for only a short period around noon, and may remain closed all day when the skies are dark with clouds.  The flowers can self-pollinate, which is useful when the period for pollinators to enter the flower is so narrow.  A typical flower blooming in July follows.

Portulaca smallii Small's Purslane Flower

Portulaca smallii
Small’s Purslane
Flower

A wider view shows the leaf shape, which is generally lance-like in outline, and rounded and cylindrical in shape.

Portulaca smallii Small's Purslane Leaves

Portulaca smallii
Small’s Purslane
Leaves

There is another, closely related portulaca at Mitchell Mill – Portulaca amilis (Paraguayan Purslane).  This plant is common and widespread in the area, and also grows on the flatrock soils, sometimes directly beside P. smallii.

Portulaca amilis can be distinguished from Portulaca smallii by its larger, dark pink flowers, and its flatter, wider leaves that often appear like the blades of a fan.

Portulaca pilosa Pink Purslane Flower

Portulaca amilis
Paraguayan Purslane
Flower

Although the preponderance of germination takes place in spring and summer, P. smallii seeds are capable of germinating throughout the growing period.  Below are photos of seedlings estimated to have germinated in late August or  September.  The scrolling vein patterns stand out clearly in these tiny plants.

Portulaca smallii Small's Purslane Seedling

Portulaca smallii
Small’s Purslane
Seedling

Portulaca smallii Small's Purslane Seedling

Portulaca smallii
Small’s Purslane
Seedling

Both portulaca species at Mitchell Mill begin to decline in October and by Thanksgiving, most plants have disappeared completely or there is only a remnant stem or dead leaves.   Pictured below are several plants that have expired but are still relatively well preserved in late November.  Portulaca smallii is directly below, followed by Portulaca amilis.

Portulaca smallii Small's Purslane Dead Plant

Portulaca smallii
Small’s Purslane
Expired Plant

 

Portulaca pilosa Pink Purslane Dead Plant

Portulaca amilis
Paraguayan Purslane
Expired Plant

Portulaca smallii is a protected plant in North Carolina: Status – Threatened (T); Rank -Imperiled (S2); Global Rank – Vulnerable (G3).  Although most plants are found on granite outcrops and flatrocks, they have also been reported on diabase flatrock.

Herb Amyx

 

 

 

 

 

 

 

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2 Responses to Portulaca smallii (Small’s Purslane) at the Mitchell Mill State Natural Area

  1. Arleigh Birchler says:

    Thanks, Herb. This one is on my List of 500, but I did not see it when I visited Mitchell’s Mill a few times a few years back.  I did get some nice shots of some of the other plants on my list during those visits. Portulaca smallii, Small’s purslane, Portulacaceae, forb,  200 to 600-(900) ft above sea level,blooms Jun-Oct, Threatened{granit, flatrock, diabase, glade, cedar, field, lime, legrand,soil, disturb,  endemic, schafale, weakley} Wake – Mitchells Mill Granitic Flatrock  282 to 296 ft asl, 35.92, -78.39 {granit, outcrop, bare, rock}{soil, gravel, typic, accumul, sand, rains}{flatrock, natur, river, plant, rare, mill, threaten, piedmont,small, moss, spring,  virgin, neuse, endemic, animal, wood, coast, plain, pine, pool, shallow, lichen,  legrand,salamander, shrub}  Arleigh Birchler “Wild Azalea Home”

    ** Sent from my Intergalactic Star Cruiser **

    From: News from Rockcliff Farm To: arleigh.birchler@yahoo.com Sent: Friday, November 28, 2014 7:32 AM Subject: [New post] Portulaca smallii at the Mitchell Mill State Natural Area #yiv0078579838 a:hover {color:red;}#yiv0078579838 a {text-decoration:none;color:#0088cc;}#yiv0078579838 a.yiv0078579838primaryactionlink:link, #yiv0078579838 a.yiv0078579838primaryactionlink:visited {background-color:#2585B2;color:#fff;}#yiv0078579838 a.yiv0078579838primaryactionlink:hover, #yiv0078579838 a.yiv0078579838primaryactionlink:active {background-color:#11729E;color:#fff;}#yiv0078579838 WordPress.com | B. W. Wells Association posted: “Portulaca smallii (Small’s Purslane) is a rare, protected plant, endemic to the thin soils of granite flatrocks and outcrops in the Piedmont regions of Virginia, North Carolina, and Georgia.  The Mitchell Mill State Natural Area contains the largest grani” | |

  2. Thanks for your comments Arleigh. The best time to find Portulaca smallii at Mitchell Mill is summer. Good numbers can be found on the large flatrocks right off Route 96, and there are also plants at several locations on the Pulleytown Rd side of the flatrocks.

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