Flora Pittsburghensis

Author: Father Pitt

  • Spotted Knapweed (Centaurea maculosa)

    These beautiful flowers, close relatives of the garden Bachelor’s Button (Centaurea cyanus), seem to be found almost exclusively along railroads. The color is variable from purple through white, but this purplish pink is by far the most common color. This plant grew along the railroad near the river on the South Side, where it was blooming in the middle of June.

    Gray describes the genus and the species:

    CENTAUREA L. STAR THISTLE
    Heads many-flowered; flowers all tubular, the marginal often much larger (as it were radiate) and sterile. Receptacle bristly. Involucre ovoid or globose, imbricated; the bracts margined or appendaged. Achenes obovoid or oblong, compressed or 4-angled, attached obliquely at or near the base; pappus setose or partly chaffy, or none. Herbs with alternate leaves; the single heads rarely yellow. (Kentaurie, an ancient Greek plant-name, poetically associated with Chiron, the Centaur, but without wholly satisfactory explanation.)

    C. maculosa Lam. Pubescent or glabrate, with ascending rather wiry branches; involucre ovoid-cainpanulate, in fruit becoming open-campanulate; the outer and middle ovate bracts with rather firm points and with 5-7 pairs of cilia at the dark tip; innermost bracts elongate, entire or lacerate; corollas whitish, rose-pink, or purplish, the marginal falsely radiate. Waste places, roadsides, etc., N. E. to N. J. (Adv. from Eu.)

  • Cow Vetch (Vicia cracca)

    A European import cultivated for fodder, Cow Vetch tends to be found wherever livestock is nearby. The vines twine through other less decorative weeds, and the beautiful blue-purple flowers light up the edges of fields. This patch grew in a sunny meadow near Cranberry, where it was blooming in the middle of June.

    Gray describes the genus and the species:

    VICIA [Tourn.] L. VETCH. TARE

    Calyx 5-cleft or 5-toothed, the 2 upper teeth often shorter, or the lowest longer. Wings of the corolla adhering to the middle of the keel. Stamens more or less diadelphous (9 and 1); the orifice of the tube oblique. Style filiform, hairy all round or only on the back at the apex. Pod flat, 2-valved, 2-several-seeded. Seeds globular. Cotyledons very thick, remaining under ground in germination. Herbs, mostly climbing more or less by the tendril at the end of the pinnate leaves. Stipules half-sagittate. Flowers or peduncles axillary. (The classical Latin name.)

    V. cracca L. Appressed-pubescent; leaflets 8-24, oblong-lanceolate, strongly mucronate; racemes densely many-flowered, 1-sided; flowers blue, turning purple (rarely white), 1-1.2 cm. long, reflexed; calyx-teeth shorter than the tube. Borders of thickets or in fields, Nfd. to N. J., w. to Ky., la., and Minn. June- Aug. (Eu.)

  • Field Pennycress (Thlaspi arvense)

    An unimposing little weed, but it delights children by producing round, flat seedpods that look like coins. This one grew in a meadow near Cranberry, where it was blooming and already seeding in the middle of June.

    Gray describes the genus and the species:

    THLASPI [Tourn.] L. PENNY CRESS
    Pod orbicular, obovate, or obcordate, flattened contrary to the narrow partition, the midrib or keel of the boat-shaped valves extended into a wing. Seeds 2-8 in each cell. Cotyledons accumbent. Petals equal.—Low plants, with root-leaves undivided, stem-leaves arrow-shaped and clasping, and small white or purplish flowers. (Name from thlaein, to crush, from the flattened pod.)

    T. arvense L. (FIELD P. or MITHRIDATE MUSTARD.) Smooth annual; lower leaves wing-petioled, the upper sagittate-clasping; broadly winged pod 1.2 cm. in diameter, deeply notched at top; style minute. Waste places; not common, except along our northern borders, where too abundant and called “FRENCHWEED.” (Nat. from Eu.)

  • Long-Leaved Starwort (Stellaria longifolia)

    Also called Long-Leaved Stitchwort, this is a remarkably delicate little plant whose ethereally insubstantial stems and leaves make it seem as though the starry little flowers are floating in the air. It likes an overgrown meadow; this one was growing among clovers and cinquefoils in a meadow near Cranberry, where it was blooming in the middle of June.

    A good description from Mathews’ Field  Book of North American Wild Flowers:

    A tall very slender species with many branches, the stem with rough angles, and the light green leaves small and lance-shaped. The tiny flowers like white stars, with five white petals so deeply cleft that they appear as ten, sepals nearly equalling the petals in length. 10-20 inches high. In wet grassy places everywhere.

    Gray describes the genus and the species:

    STELLARIA L. CHICKWEED. STARWORT
    Sepals 4-5. Petals (white) 4-5, deeply 2-cleft, sometimes none. Stamens 8, 10, or fewer. Styles 3, rarely 4 or 5, opposite as many sepals. Pod ovoid, 1-celled, opening by twice as many valves as there are styles, several-many-seeded. Seeds naked. Flowers solitary or cymose, terminal or appearing lateral by the prolongation of the stem from the upper axils. (Name from stella, a star, in allusion to the star-shaped flowers.) ALSINE. in part, not Wahlenb.

    S. longifolia Muhl. Stem erect, weak, often with rough angles (2-5 dm. high); leaves linear, acutish at both ends, spreading; cymes scaly-bracted, at length lateral, peduncled, many-flowered, the slender pedicels spreading or deflexed; fruit pale straw-colored; seeds smooth. (Alsine Britton.)—Grassy places, Nfd. to Md., and westw. June, July. (Eu.)


  • Alsike Clover (Trifolium hybridum)

    Red Clover (T. pratense) is more common and very similar, and grows in most of the same places. The best way to tell the difference is by the leaves, which in Red Clover usually (but not always) show a chevron pattern but are unmarked in Alsike Clover; and by the color of the flowers, which in Alsike Clover is less magenta and more pale rosy pink, with young white flowers in the center of the head. In fact, it does look like something halfway between Red Clover and White Clover (T. repens), which may account for the specific name hybridus for a plant that is not a hybrid.

    This plant grew in a meadow near Cranberry, where it was blooming in the middle of June.

    Gray describes the genus and the species:

    TRIFOLIUM [Tourn.] L. CLOVER. TREFOIL

    Calyx persistent, 5-cleft, the teeth usually bristle-form. Corolla mostly withering or persistent; the claws of all the petals, or of all except the oblong or ovate standard, more or less united below with the stamen-tube; keel short and obtuse. Tenth stamen more or less separate. Pods small and membranous, often included in the calyx, 1-6-seeded, indehiscent, or opening by one of the sutures. Tufted or diffuse herbs. Leaves mostly palmately (sometimes pinnately) 3-foliolate; leaflets usually toothed. Stipules united with the petiole. Flowers in heads or spikes. (Name from tres, three, and folium, a leaf.)

    T. HYBRIDUM L. (ALSIKE C.) Resembling T. repens, but the stems erect or ascending, not rooting at the nodes; leaflets ovate, rounded at apex; flowers rose-tinted. Generally common. (Introd. from Eu.)