This section of the book is from the "Wild Flowers Worth Knowing" book, by Neltje Blanchan. Also available from Amazon: Wild Flowers Worth Knowing
ST. JOHN'S-WORT FAMILY - Hypericaceae: Common St. John's-wort
Hypericum perforatumFlowers--Bright
yellow, 1 in. across or less, several or many in terminal clusters.
Calyx of 5 lance-shaped sepals; 5 petals dotted with black; numerous
stamens in 3 sets; 3 styles. Stem: 1 to 2 ft. high, erect, much
branched. Leaves: Small, opposite, oblong, more or less
black-dotted. Preferred Habitat--Fields, waste lands,
roadsides. Flowering Season--June-September. Distribution--Throughout
our area, except the extreme North; Europe and Asia. "Gathered upon a
Friday, in the hour of Jupiter when he comes to his operation, so
gathered, or borne, or hung upon the neck, it mightily helps to drive
away all phantastical spirits." These are the blossoms which have been
hung in the windows of European peasants for ages on St. John's eve,
to avert the evil eye and the spells of the spirits of darkness.
"Devil chaser" its Italian name signifies. To cure demoniacs, to ward
off destruction by lightning, to reveal the presence of witches, and
to expose their nefarious practices, are some of the virtues ascribed
to this plant, which superstitious farmers have spared from the scythe
and encouraged to grow near their houses until it has become, even in
this land of liberty, a troublesome weed at times. "The flower gets
its name," says F. Schuyler Mathews, "from the superstition that on
St. John's day, the 24th of June, the dew which fell on the plant the
evening before was efficacious in preserving the eyes from disease. So
the plant was collected, dipped in oil, and thus transformed into a
balm for every wound." Here it is a naturalized immigrant, not a
native. A blooming plant, usually with many sterile shoots about its
base, has an unkempt, untidy look; the seed capsules and the brown
petals of withered flowers remaining among the bright yellow buds
through a long season.

The Shrubby St. John's-wort (H. prolificum) bears yellow blossoms, about half an inch across, which are provided with stamens so numerous, the many flowered terminal clusters have a soft, feathery effect. In the axils of the oblong, opposite leaves are tufts of smaller ones, the stout stems being often concealed under a wealth of foliage. Sandy or rocky places from New Jersey southward best suit this low, dense, diffusely branched shrub which blooms prolifically from July to September.
Farther north, and westward to Iowa, the Great or Giant St. John's-wort (H. Ascyron) brightens the banks of streams at midsummer with large blossoms, each on a long footstalk in a few-flowered cluster.
 
Continue to: