Carderock – Marsden Tract Report

skink posing on rockface

Plants seen on May 2; those that were flowering are probably close to done by today.






Antennaria plantaginifolia (plantain-leaved pussy toes): most in seed




Aplectrum hyemale (puttyroot orchid): one flower on one spike open
Arisaema triphyllum (jack-in-the-pulpit): flowering
Asimina triloba (pawpaw): done flowering
Boechera laevigata (smooth rock cress): in seed
Cerastium arvense (field chickweed): a few still flowering but past peak

Chionanthus virginicus (fringetree): glorious flowering; follow your nose, they’re fragrant




Claytonia virginica (spring beauty): only a handful left
Comandra umbellata (bastard toadflax):  no flowers, though there were buds 2 weeks ago; did I miss it?!
Erigeron pulchellus (Robin’s plantain): flowering
Geranium maculatum (wild geranium): done
Hesperis matronalis (dame’s rocket; alien): blooming
Heuchera americana (alumroot): flowering
Hieracium venosum (rattlesnake weed): flowering
Houstonia caerulea (azure bluets): still flowering but past peak
Hydrophyllum virginianum (Virginia waterleaf): flowering but in decline
Kalmia latifolia (mountain laurel): lots of buds just ready to burst open
Mertensia virginica (Virginia bluebells): all done
Micranthes virginiensis (early saxifrage): saw one plant blooming; effectively done
Mitchella repens (partridgeberry): budding up
Myosotis verna (spring forget-me-not): done
Osmorhiza claytonii (sweet cicely): done
Oxalis stricta (common yellow woodsorrel): going strong
Oxalis violacea (violet woodsorrel): still blooming
Packera aurea (golden ragwort): done

Penstemon hirsutus (hairy beardtongue): peak bloom



Phacelia covillei (Coville’s phacelia): done
Phlox divaricata (wild blue phlox): very few left; effectively done
Phlox subulata (moss phlox): only a few left; effectively done
Polygonatum biflorum (Solomon’s seal): blooming
Potentilla canadensis (dwarf cinquefoil): blooming
Potentilla simplex (common cinquefoil): blooming
Ranunculus repens (creeping buttercup; alien): blooming

Robinia pseudoacacia (black locust): blooming



Rosa multiflora (multiflora rose; alien): blooming
Rubus species (dewberry): blooming
Salvia lyrata (lyre-leaved sage): still blooming but past peak
Sanicula species (snakeroot): just starting to bloom
Silene caroliniana (wild pink): done
Sisyrinchium angustifolium (blue-eyed grass): blooming
Staphylea trifolia (bladdernut): mostly done
Stellaria pubera (star chickweed): just a few left, almost done
Thalictrum coriaceum (maid-of-the-mist): blooming but past peak
Thalictrum thalictroides (rue anemone): done
Toxicodendron radicans (poison ivy): full bloom
Tradsecantia virginiana (Virginia spiderwort): full bloom
Trifolium repens (white clover; alien): blooming
Trillium sessile (toadshade): almost done
Vaccinium stamineum (deerberry): blooming
Valeriana pauciflora (long-tube valerian): blooming, just past peak
Valerianella species (cornsalad): blooming
Veronica serpyllifolia var. serpyllifolia (thyme-leaved speedwell): blooming
Viola palmata (early blue violet): blooming
Viola sororia (common blue violet): done

and a black rat snake

Variations on a Theme: Venus’ Pride and Longleaf Bluets


Houstonia species, Rubiaceae

Nationwide there are 18 species of Houstonia, only five of which are found in Maryland; one of those one is found only in Garret County. In the Piedmont, two of these species (azure bluet and Venus’ pride) are rather widespread, and two (longleaf bluet and small bluet) not so much.

Last June I thought I’d found both Venus’s pride and longleaf bluet along the C&O Canal near the Marsden Tract. This year, when I went in search of them I found only Venus’ pride, but I did find longleaf bluet on Sugarloaf Mountain. Here’s a little primer about the two. Their flowers are almost identical; it’s the leaves that differentiate them.

I took measurements of only a few plants, and each patch of plants contained only a few individuals, so consider this casual observation rather than proper science.

A note about color: these flowers were all vaguely purple… in the right light. In some of these photos they’ll look white, which is pretty much how they appear in strong sunlight. In shade the purple, while faint, is more apparent. Despite the moniker “bluet”, they never seem blue.

There’s a little glossary at the end.


Houstonia longifolia
common names: long-leaved bluet, longleaf summer bluet

  • perianth about 1/4″ long
  • corolla about 3/16″ wide
  • plant height estimated 4-6″
  • leaves opposite, 1/2′ to 3/4′ long, linear shape, one-nerved, margins entire, stipules present

H. longifolia is present in Maryland in parts of the Piedmont and one section of the Coastal Plain, but is found mostly in the Blue Ridge and Ridge and Valley physiographic provinces. BONAP shows it as rare where present in Maryland, but it’s not on the state DNR list of rare, threatened, and endangered plants.

Taxonomic note: MD DNR lists another species, H. tenuifolia, as S1/endangered. However that species is not recognized by ITIS, which considers is a synonym for H. longifolia. What that means for conservation efforts I have no idea.

H. longifolia grows mostly in the Appalachians and Ozarks, and in parts of the Upper Midwest. It’s endangered in Connecticut and Massachusetts, special concern in Maine, and historical in Rhode Island.








Houstonia purpurea
common names: purple bluet, Venus’ pride, woodland bluet, large bluet

  • perianth about 3/8″ long
  • corolla about 3/16″ wide
  • plant height estimated 4-6″
  • leaves opposite, 1″‘ long, oval shape, three-nerved, margins entire but ciliate, stipules present

H. purpurea is present in the Maryland Piedmont and parts of Coastal Plain. Per BONAP, it ranges through the Appalachians, the Ozarks, and much of the South, but not the Upper Midwest.

ITIS lists three varieties, two of which are endangered in New York; the third is endangered in North Carolina and Tennessee and is also on the federal endangered species list.







perianth: the sepals and petals of a flower, collectively
corolla: the petals of a flower
ciliate: fringed with hairs
stipule: small, leaf-like growth where leaf meets stem

BONAP the Biota of North America Program
ITIS the Integrated Taxonomic Information System
Maryland Biodiversity Project