St Patrick’s Day!

Saint Patrick’s Day was made an official Christian feast day in the early seventeenth century and is observed by the Catholic Church. It is a public holiday in the Republic of Ireland, Northern Ireland, the Canadian province of Newfoundland and Labrador, and the British Overseas Territory of Montserrat. According to St. Patrick’s Day lore, Patrick used the three leaves of a shamrock to explain the holy trinity: the Father, the Son, and the Holy Spirit. Additionally, St. Patrick’s Day revelers wear a shamrock out of tradition. However, people in Ireland hoping to wear an authentic shamrock may be out of luck this year. For example, Trifolium dubium, the wild-growing, three-leaf clover that some botanists consider the official shamrock, is in short supply, according to media reports. Two genera are symbolized in St. Patrick’s Day: Oxalis and Trifolium. The common name, three-leaf cloves, is scientifically known as Trifolium, whereas Oxalis is the genus in which it is the proper form of the three leaves with love shape.

The Oxalis is a large genus of five hundred or so species of bulbous, rhizomatous, and fibrous-rooted perennials and a few small, weak shrubs under the family Oxalidaceae. Though found worldwide, many Oxalis species are native to South Africa and South America. Some have become garden and greenhouse weeds which, though pretty in flower, have given a bad name to the genus; most species listed here are more restrained in growth and make choice additions to the garden.

The leaves are always compound, divided into three or more heart-shaped or deeply two-lobed leaflets in a palmate arrangement (like clover). The funnel-shaped flowers are usually pink, white, or yellow and are carried in an umbel-like cluster on slender stalks. Most species grow from bulbs or corms, which multiply readily. A position in the sun or part-shade suits most, along with a mulched, well-drained soil and moderate water. Propagation can be done by dividing the bulbs or seeds in the fall (autumn).

Wood sorrel, scientifically known as Oxalis acetosella, is native to temperate North America and Eurasia. This delicate perennial has a creeping, prostrate habit and bears nodding white flowers with purple veins in spring-early summer. It is a woodland plant growing in excellent, moist soil, often in deep shade. It is a modestly pretty plant, seldom more than four inches high. Pink-flowered forms are sometimes cultivated.

Besides, Oxalis adenophylla This bulbous species from the southern Andes of South America makes a small mound to three inches high. The leaves consist of up to twelve units of two-lobed leaflets. Suitable for a rockery, it bears open, purple-pink flowers with darker centers from late spring to early summer. Oxalis articulata is a Paraguayan species with numerous fleshy, caterpillar-like rhizomes that disperse when soil is disturbed. In some mild, moist climates, it has become a minor nuisance. The three-lobed, hairy edged leaves are long-stalked, and the rose-pink flowers are borne above the foliage in dense, showy sprays in summer and fall (autumn).

Moreover, Oxalis citrina is a native of cooler areas of South Africa and the Americas. This charming little plant has the brightest golden-yellow flowers of any oxalis and is prized by collectors of rare bulbs. It flowers in spring or early summer. Then, Oxalis enneaphylla, commonly called scurvy grass, is native to the far south of South America and the Falkland Islands. This clump-forming perennial produces tufts of fleshy, hairy, blue-gray leaves with up to twenty folded leaflets and grows only about three inches high. It bears fragrant, extensive, white to deep pink-red flowers from late spring into early summer; it spreads slowly by deep scale-covered rhizomes.

In addition, most oxalises have leaves like clovers, but Oxalis hirta perennial from South Africa’s Western Cape Province is different. Growing from bulbs, it produces elongated, closely crowded stems about eight inches long, making a bushy, crinkly leafed plant that covers itself for weeks in autumn and winter with deep pink flowers with yellow throats about eighteen millimeters wide. Oxalis ‘Tone Hecker’ Believed to have originated as a hybrid between the South American species Oxalis enneaphylla and O. laciniata, this summer-flowering plant bears tunnel-shaped, lilac-blue flowers marked with darker veins. It makes a tiny mound of gray foliage only two inches high and about two to three inches across.

Oxalis massoniana is an orange-toned flower that makes Oxalis masoniana a novelty. It comes from southern Africa, and it was named after Francis Masson, a Scot who made notable collections in South Africa in the late eighteenth century. Oxalis oregana, commonly referred to as howood sorrel, originated from the Western USA and Canada spreads by creeping rhizomes and forms large, dense mats in moist, shady woodlands and forests. It grows ten inches high and has one inch or longer, broadly heart-shaped dark green leaflets. Rosy pink to white flowers Tre borne on solitary stems from spring to fall (autumn).

Oxalis pes-caprae is commonly known as permuda buttercup or soursob in frost-free climates, and this South African species will take over the garden; it has become a bad agricultural weed in some winter-rainfall areas with light-textured soils. It is a bulbous, stemless perennial that grows to eighteen inches tall with tufts of crowded, erect, or spreading, succulent bright green leaves on long stalks. Its bright yellow flowers appear in great profusion in spring or early summer on tall stems.

Oxalis purpurea, also called Oxalis variabilis, is one of the showiest species in the genus, this South African native has large flowers in pink, rose, lilac, or white; all have soft yellow centers. Clover-like leaves arise from bulbs to form a mound only four inches high; the deep green leaflets have purple undersides, and the flowers appear from late fall (autumn) until early spring. It spreads slowly, but is not invasive.

Oxalis tetraphylla or Oxalis deppei, usually called lucky clover or good luck plant is a Mexican species that is a tuft-forming, bulbous perennial. Its crowded leaves are generally divided into four roughly triangular leaflets up to six centimeters long with a basal blotch of dull purple. It produces loose sprays of funnel-shaped, deep reddish-pink flowers with a yellow throat in spring and summer. This plant needs a protected position. It reaches a height of six inches and a spread about the same ‘Iron Cross’ has a dark purplish mark at the base of each leaflet.

Oxalis tuberosa (commonly called OCA) is believed to have originated in the Northern Andes, and this species is the second only to the potato in importance as a root vegetable in the cooler parts of South America. Its knobbly translucent tubers are about two inches in diameter and maybe round or elongated with the color varying from white to yellow or pink, sometimes with darker streaks. Only the white-tubered form will flower. Above ground, it forms a tangle of weak stems with plain green three-pointed leaves; the small flowers are yellow. It is hardy to most frosts.

Out of all species in Oxalidaceae, Oxalis corniculate is a medicinally important herb that is highly used for its anti-oxidant, anti-fungal, anthelmintic, anti-inflammatory, analgesic, astringent, anti-cancer, depurative, diuretic, emmenagogue, anti-microbial, febrifuge, cardio-relaxant, lithontripic, stomachic, and styptic properties globally. This is because it possesses phytochemicals, which has glycosides, phytosterols fatty acids, galactoglycerolipid, botulin, methoxyflavones, β-sitosterol, hydroxybenzoic acid, ethyl gallate, and apigenin.

On the other hand, the Trifolium taxa are among the most important genera of the leguminous family, both in their agricultural value and the number of species, about three hundred species. This large genus of annuals, biennials, or perennials consists of about two hundred and thirty species, some semi-evergreen. They are found under the family of Fabaceae. Widespread throughout temperate and subtropical regions, they are absent from Australia.

These species have rounded, usually three-parted leaves and heads of pea-like flowers. The individual blooms are often tiny, making the head resemble a single blossom. Many species become invasive but have agricultural uses, while others are suitable for banks or rock gardens. The clovers will grow in the sun or part-shade. All species are very frost-hardy. It can be propagated from seed in fall or by division in spring. Most species self-seed readily.

In Turkish folk medicine, some Trifolium species like T. repens, T. arvense, T. pratense are used as expectorants, analgesics, antiseptics, and against rheumatism ashes. Research has proven that Trifolium contains beneficial phytochemicals such as flavonoids, isoflavonoids, chalcones, and coumarins. There is relatively little information on the volatile compounds produced by Trifolium species.  

A red clover, scientifically known as Trifolium pratense, is a meadow, creeping, or craw clover. They are coarse, erect, or decumbent perennial up to twenty-four tall plants, one of the most important forage plants. It bears large, globose heads of pink to purple flowers from late spring to early autumn. It is native to Europe and is a popular pasture clover. It is occasionally sold in cultivated forms, and its flowers are popular with apiarists. Apart from that, it has been used by the Oriental and the European cultures, and more recently also by the Americans, as a medicinal herb for the treatment of eczema and psoriasis. Traditionally, Americans valued red clover for treating external skin problems and lung, nervous and reproductive system ailments.

In addition, white clover is a European species with low creeping stems that will root at the nodes. The trifoliate leaves have serrated margins and a whitish mark at the base. The white or green flowers are produced in globular terminal clusters from spring to fall and into winter in warmer climates. T. repens ‘Purpurascens Quadrifolium’ is grown for its bronze-green four parted foliage variably edged with bright green. Although unwelcome in fine turf, white clover is a vital pasture plant and honey source. Furthermore, Trifolium uniflorum is a low-growing creeping and clump-forming species from the eastern Mediterranean. It has trifoliate leaves, and the lilac flowers are borne in terminal clusters in the summer.

Further readings:

Dreyer, L. L. (1998). A palynological review of Oxalis (Oxalidaceae) in southern Africa.

Abberton, M. T. (2007). Interspecific hybridization in the genus Trifolium. Plant Breeding126(4), 337-342.

Sabudak, T., & Guler, N. (2009). Trifolium L.–a review on its phytochemical and pharmacological profile. Phytotherapy Research: An International Journal Devoted to Pharmacological and Toxicological Evaluation of Natural Product Derivatives23(3), 439-446.

Badwaik, H., Singh, M. K., Thakur, D., Giri, T. K., & Tripathi, D. K. (2011). The botany, chemistry, pharmacological and therapeutic application of Oxalis corniculata Linn-a review. International Journal of Phytomedicine3(1), 01.

Kolodziejczyk-Czepas, J. (2012). Trifolium species-derived substances and extracts—Biological activity and prospects for medicinal applications. Journal of ethnopharmacology143(1), 14-23.

Srikanth, M., Swetha, T., & Veeresh, B. (2012). Phytochemistry and pharmacology of Oxalis corniculata Linn.: A review. International journal of pharmaceutical sciences and research3(11), 4077.