Hypericum aegypticum is a species of flowering plant of the St. John's wort family (Hypericaceae) which is native to the Eastern Mediterranean. It was described by Carl Linnaeus in the second volume of his Species Plantarum in 1753, who named it after Egypt despite it not being distributed there. The plant is commonly known as shrubby St. John's wort or Egyptian St. John's wort in English. Like other members of section Adenotrias, it is found among limestone rocks in coastal areas. While it has been evaluated as threatened on the island of Malta, the species has no legal protections. The species is a shrub or shrublet that grows up to 2 meters (6.6 feet) tall with many branches, each having a single small flower with five yellow petals and many stamens. Its leaves lack hairs, and have densely patterned glands and large primary veins. The species is notable for its heterostyly, a trait which within the Hypericum genus is unique to section Adenotrias, and exhibits one of two heterostylous flower types called "pins" and "thrums". It has three subspecies, which vary in their distribution and phytochemical makeup.
Description
Hypericum aegypticum is a shrub or shrublet that varies in height from 0.05 to 2 meters (0.16 to 6.56 ft) tall. It grows in a crowded, spreading pattern, with its stems stretching out from the center of the plant. The branches grow roughly perpendicular from these stems, but can also spread out in different directions. It has a chromosome number of 2n=20.
Stems The stems of Hypericum aegypticum usually have two visible lines running along their length, but can sometimes have four. When the plant is young, the stems are a flatter shape with two edges (ancipitous), but quickly become more cylindrical as the plant matures. In a cross-section, the profile of the stems is circular and lacks wing-like extensions. They have a vessel density of roughly two vessels per square millimeter of stem, with each of these vessels measuring 15 micrometers in diameter. In between the nodes where the leaves branch from (in the internodes), there are small leaf-like structures which are shorter than the true leaves. The xylem in the stems, a type of transport tissue, differs from other similar species of Hypericum. The xylem of H. aegypticum is diffuse; it is spread evenly throughout the stem. In other similar species, the xylem is ring-porous and more dense in a series of concentric rings. There are two secretory structures in the stems: small secretory canals in the phloem and many large secretory canals in the cortex.
Leaves The leaves of Hypericum aegypticum are free and range from sessile to shortly petiolate. They persist for around two seasons. The blades are 3–18 millimeters (0.1–0.7 inches) long and 1–5 millimeters (0.04–0.20 inches) wide. Their shape is elliptic or narrowly oblong. The leaves are the same color as the rest of the plant and have a texture similar to that of leather. The shape of their tip can range from acute to obtuse and the base of the leaf is wedge-shaped. The leaves lack hairs (trichomes) on both the top and bottom. They have one pair of lateral veins, with the midrib sometimes branched and visible beneath them. Their primary veins are very large and straight and are highly rigid. The secondary veins branch off at acute angles of wide divergence, and some tertiary veins with a branched pattern are also present. The laminar and marginal glands are dense. Unlike some species of Hypericum, such as H. perforatum, H. aegypticum lacks black nodules on its leaves. Instead, it has small translucent glands which measure 54 by 45 micrometers and are found in the mesophyll. The upper sides of the leaves have an outer layer (epidermis) made of cells with linear walls and rounded corners. This upper side also has stomata that are surrounded by smaller cells. The lower side of the leaves have a similar composition to the upper side, but with a higher density of stomata. On both sides, there is a cuticle that extends over the entire surface, even over the guard cells, which makes them very hard to distinguish. This thick cuticle leads to increased impermeability in areas where there are encrusted deposits.
Inflorescence Hypericum aegypticum is one-flowered, and its inflorescence is terminal and grows from around four axils below. It has short flowering branches past a "sterile" region which lacks them. These branches grow from around eleven different nodes. However, some plants lack the sterile region and can have flowers or flowering branches from up to twenty-two nodes. The inflorescence is similar in appearance to a spike, with longer branches below the flowering region. The bracts are often absent, but when they are present they are leaf-like in appearance, with a clasping calyx and several types of glands. The pedicels are very short or absent altogether.
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