Calathea (Calathea spp. and hybrids.) is a genus of neotropical rhizomatous herbaceous perennial plants; members of which are referred to generally as Calatheas. ‘Prayer plants’ is a colloquial term that refers to members of genus Maranta, to which genus Calathea is closely-related. They’re all considered to be ‘prayer plants’.
Two most common species or cultivars are Calathea veitchiana ‘Medallion’ (Medallion calathea) and Calathea lancifolia (Rattlesnake calathea). Calathea leaves are used in Brazil for handicraft and food wrapping. Because of the diversity of the leaf shapes, baskets are weaved with the lanceolate leaves, and food is wrapped with the wider leaves. The colorful leaf markings of most Calatheas make them economically important as houseplants, and their popularity has been growing with the development of new cultivars.
Say a little prayer for you
Marantaceae, named so for the tendency of plants in this family to droop, or ‘pray’ at night. The daily movements of the plants leaves is known as nyctinasty. Various plants in this family move their leaves up at nighttime, and lower them in the daytime in accordance to a circadian rhythm. They move their leaves by changing the water pressure in their pulvini, the swollen nodes at the base of the leaf, along the leaf stalk (petiole). It is believed that these movements are meant to follow the sun’s movement in the sky in order to maximize light absorption.
Like members of Oxalidaceae and Fabaceae, these plants have enlarged pulvini (singular - pulvinus), which are fattened joint-like structures on the leaf petioles. When the leaves are to be raised, the cells within these structures swell with water, due to signalling from Pfr (a plant signalling molecule) and solute transport. Pfr is created from Pr, when the plant receives with red light from the sun. Pfr is the active form, whereas Pr is the inactive form, created when the plant receives residual far-red light. Each is named after the wavelength of light which converts it. It is through the Pr/Pfr cycles that the plant is able to tell when it is daytime.
These rhizomatous perennial herbs are native to moist or swampy tropical forests, particularly in the Americas but also in Africa and Asia. Members of the family vary from plants with slender, reedlike stalks to leafy spreading herbs to dense bushes nearly 2 m (about 6.5 feet) high. They have rhizomes, which are usually white, and some species are ethnobotanically important. The most well-known species in the family is arrowroot, Maranta arundinacea, native to the Caribbean, is grown in parts of the Caribbean, Australasia, and sub-Saharan Africa for its easily digestible starch known as arrowroot. Various species of Calathea, Maranta, and Stromanthe are grown for their ornamental foliage. Some Calathea species have edible tubers, and others produce wax, some of which are harvested and used, like, Calathea lutea, grown to make waterproof baskets because of its durable, waxy leaves.
Genetic evidence suggests that this family originally diverged while in Africa, but there currently exist species which are native to the neotropics (the tropical Americas). It is likely that, while the continents were joined as Pangaea, this family was widespread across Gondwanaland (the single landmass of S. America, Africa, Antarctica, Australia). After the continents split into their current landmasses, there was an isolation of the neotropical species. Some phylogenetic analyses place Calathea and Maranta as polyphyletic--some neotropical species are more closely-related to the African species than they are to each other. This evidence is biological supporting evidence for Pangaea, and it is common for families to be distributed across Africa and South America.
Did you know?
Robert Brown, the same naturalist who described Brownian Motion, as later described by Einstein, had travelled the world collecting samples of various plants, and had established the Prayer Plant family, Marantaceae. He had chosen the name Marantaceae, likely after the indigenous word “Maranta”, which refers to edible arrowroots.
The Sill has some quick tips for calathea care as a reference when you need it.
Low to medium indirect light.
Water once weekly. Allow soil to half-dry out before watering. Soil surface should be dry to the touch. Soil should be almost dry about 2" down.
Normal room humidity. If edges burn or crisp, raise the humidity.
65°F-85°F (18°C-30°C). It’s best not to let it go below 60°F (15°C).
Prone to foliar fungal infections. Keep leaves dry. May get spider mites and mealybugs. Treat spider mites and mealybugs as soon as they appear with weekly sprays of horticultural (Neem) oil and regular wipe-downs of the plant.
SYMPTOM: Leaves turning brown and crispy at leaf edges
CAUSE: Under watered, low humidity, high salts, or potassium deficiency
SYMPTOM: Leaf curl
CAUSE: Under watered
SYMPTOM: Yellowing, possible black stems, mushy, falling apart
CAUSE: Rot or root disease; overwatering
PRECAUTIONS: Generally ok to cats, dogs, and humans if consumed. Best practice is always to keep houseplants out of reach of small children and pets.