Orchid Knowledge Introduction: A Comprehensive Guide to Orchids

Roots

The roots of terrestrial orchids form a clustered fibrous root system, fleshy, occasionally producing segmented branch roots from the fibers, and orchid roots generally have no root hairs. Generally, the roots of Cymbidium goeringii (Spring Orchid) are relatively thin, about 0.4 cm in diameter; those of Cymbidium faberi (Faber's Cymbidium) about 0.5 cm; while those of Cymbidium ensifolium (Four-season Orchid), Cymbidium qiubeiense (Autumn Orchid), Cymbidium kanran (Cold Orchid), and Cymbidium sinense (Chinese Cymbidium) are slightly thicker and longer than the above. Orchid roots store abundant water and nutrients. According to root structure, they can be divided into three parts: inner, middle, and outer. The outermost layer is the root bark tissue surrounding the entire root, mainly serving to absorb and retain water. Therefore, orchids should not be watered too frequently; otherwise, overly wet soil can easily cause root rot. Inside the root bark is the cortical tissue, whose cells are all living cells; some contain needle-like crystals, and some contain symbiotic root fungi. When a fleshy root breaks, there is a yellowish-white fibrous core about 0.1 cm thick inside, called the central core, which is not easily broken. In potted orchid roots cultivated for many years, when dry, healthy roots appear off-white; young roots are mostly tender white when growing; if exposed on the pot surface or outside the soil, due to moisture, they appear greenish or dark gray. Orchid roots have orchid fungi living symbiotically with them, thereby obtaining more nutrients and promoting lush growth. This is why in traditional Chinese practice, when collecting and transplanting orchids, some native soil must be kept, and sharp tools must be avoided for digging - this is the reason.

　　

Stem

Terrestrial orchids have no obvious stem, only a distinction between rhizome and flower stem. At the junction of roots and leaves there is a swollen pseudobulb, whose forms include columnar, spindle-shaped, oval, spherical, and flattened spherical, all growing upward, fully exposed or slightly exposed above the soil surface, and it should not be completely buried in soil when planting. The size of pseudobulbs varies by species; for example, Cymbidium goeringii (Spring Orchid) and Cymbidium faberi (Faber's Cymbidium) are generally about 1-1.5 cm tall and about 1 cm wide, while other types are more robust. A healthy pseudobulb is entirely covered by green leaves on the outside; when it ages, the leaves wither and shrink. An exposed pseudobulb appears yellow or yellow-green, and at this time withered, slender, thread-like leaf remnants remain on the pseudobulb. In Chinese orchid cultivation, pseudobulbs are commonly called lutou, putou, longtou, etc. They store nutrients and water and generally can live for three to five years. When they enter the aging stage, they can still produce new pseudobulbs. From the yellow mold period to midsummer or early autumn, leaf buds and flower buds sprout from the base of the pseudobulb. Another type of stem is the flower stem (that is, the scape, peduncle), covered on the outside by several layers of bracts.

　　

Leaves

They can be divided into two types: ordinary leaves and bracts. The leaves clustered from the pseudobulb are called ordinary leaves, linear or strap-shaped, with no obvious petiole. Leaf clusters all grow out at once, with entire margins or fine serrations on the edges, parallel veins, evergreen and hard-leathery. The leaf surface is mostly dark green, the underside lighter, and the leaf tip is sharp or rounded-obtuse. Cymbidium goeringii (Spring Orchid) leaves are about 0.4-0.8 cm wide and more than 20 cm long; Cymbidium ensifolium (Four-season Orchid) and Cymbidium kanran (Cold Orchid) are wider and longer; Cymbidium sinense (Chinese Cymbidium) is even wider, about 1.5 cm or more. The central midrib of the leaf protrudes or slightly protrudes toward the underside, supporting the orchid leaf to grow upward, so it is not easily broken even when swaying in the wind. Every five to seven or eight leaves form a bundle (each bundle is commonly called a "tube" or "zhuang" in Chinese orchid cultivation; each bundle should be counted starting from three leaves). Cymbidium goeringii (Spring Orchid) and Cymbidium faberi (Faber's Cymbidium) should standardly have 3-5 leaves per bundle, while other types have slightly more.

　　

According to traditional Chinese orchid cultivation, for the leaf types of Cymbidium goeringii (Spring Orchid) and Cymbidium faberi (Faber's Cymbidium), combined with experience with petal types, it is considered best when the leaf tip forms a groove and the pouch reaches the base. The leaf character of plum-petal types is relatively hard, while that of narcissus-petal types is glutinous. Those that are fat, broad, thick, and solid mostly produce lotus-petal or broad-petal flowers.

　　

Another type of leaf is the modified leaf wrapping the flower stem. Due to degeneration, it becomes membranous and scale-like, with a sheath-like base, commonly called a shell, and botanically called a bract. It mainly serves to protect the flower bud. The outermost two bracts at the base have hard cuticle, while the inner ones appear soft and membranous. Chinese orchid growers often use its color, veins, and sand-like mottling as a basis for identifying petal-type classification during flower bud development. Cymbidium goeringii (Spring Orchid) has five layers of bracts; when fully open, the topmost bract of the inflorescence may rise above the flower or remain lower than the flower. Cymbidium faberi (Faber's Cymbidium) and other multi-flowered stems have 7-9 layers of bracts, and the base of each flower's pedicel has a short, narrow, soft membranous wrapping leaf. The size, width, and color of the bracts of Cymbidium goeringii (Spring Orchid) and Cymbidium faberi (Faber's Cymbidium) are all related to petal type.

　　

Flowers

The flowers of the genus Cymbidium are all irregular flowers, solitary or consisting of multiple flowers of roughly equal stalk length borne on a long flower stem, arranged in a raceme. In terms of floral structure, there are six petals and one column (the gynostemium), divided into three whorls. The outermost whorl consists of three similarly shaped sepals, called the outer three petals in orchid cultivation terminology. The middle whorl of three is commonly called the inner three petals; the upper two are longitudinal and parallel, slightly shorter than the outer three petals, commonly called the petals; the lower one is commonly called the lip or tongue, hairy, scattered with red or purplish-red spots. Those with this color are called fleshy-petal flowers; if the tongue is pure green, white, or slightly yellow, they are called plain-petal flowers. The innermost layer is the column made up of stamens and pistil, commonly called the nose or fragrant part, which is the part that contains fragrance. The top of the column is the stamen, with an anther cap outside and pollen chambers inside, containing pollinia. The anther is sessile; the lower part of the pollinium has an elongated stalk, namely the caudicle, with a sticky disc at its base. At the top of the column, slightly forward and below, there is a concave cavity containing sticky fluid; this sticky fluid is often used by insects as a medium during pollination. The pistil is composed of three fused carpels, with an inferior ovary and parietal placentation; the placenta contains numerous anatropous ovules.

　　

Fruit

After the pistil of an orchid is fertilized, the petals gradually wither, while the ovary gradually swells into a green club shape. After about 6-12 months, the seed fruit matures, and the fruit skin turns from yellow-green to brown. The fruit is generally columnar with three angles; fruit shape varies by species, which helps in identification and classification. The seed fruit of Cymbidium goeringii (Spring Orchid) is relatively short and low, generally about 3-4 cm tall, while that of Cymbidium faberi (Faber's Cymbidium) is somewhat longer and thicker. The seed fruit of Cymbidium qiubeiense (Autumn Orchid) resembles that of Cymbidium ensifolium (Four-season Orchid) and Cymbidium faberi (Faber's Cymbidium). Cymbidium kanran (Cold Orchid) resembles Cymbidium sinense (Chinese Cymbidium). The fruits of Orchidaceae plants are all capsules, triangular or hexagonal, with each angle having a long ridge about 0.3 cm thick from apex to base, called the fruit column ridge. When the fruit matures, the fruit column ridge in the center of each valve plane splits open from the top of the capsule, and the valves produce inverted conical cracks, facilitating the ejection of seeds from the opening.

　　

Orchid seeds are extremely small, as fine as dust, generally long spindle-shaped, almost indistinguishable to the naked eye. Each seed weighs only 0.3-0.5 micro-milligrams. It has no endosperm, only a simple embryo, wrapped outside by a loose, transparent, water-resistant seed coat. The seed coat has many thickened lignified striations, and the embryo contains very little nutrient, mostly fat-based substances. Because orchid seeds are tiny and numerous (each capsule contains about ten thousand seeds), and the seed coat has great buoyancy and particularly strong resistance to water and moisture, after the seeds are ejected, dispersal by water flow has no adverse effect. The germination rate of orchids is very low, and the seeds are difficult to store, so it is best to sow them after maturity.