Euphorbia lactea 'Cristata'
Family: Euphorbiaceae
​Common Name: coral cactus, crested elkhorn, crested candelabra plant
Origin: Euphorbia lactea ‘Cristata’ is native to Africa and India (2,4,7).
 
Description: Euphorbia lactea ‘Cristata’ is a succulent sport of Euphorbia lactea with a cristate, fan-like head (1,2,3,4,5,6,7). This plant has a branching growing habit, with its stems being a continuous procession of fan-shaped crests (9). Each crest can grow up to 3ft high and 2ft wide, and each is ridged with undulating green-white streaking, bearing resemblance to brain coral (1,3,4). This plant has a green and whitish-grey coloration, sometimes with pink shading on its edges when sun-stressed (2,3,4,7). This plant has pairs of thick straight spines, usually found along its ridges (9). This plant develops small inconspicuous flowers, with a pink or purple coloration (1,2).
 
 
Interesting Features:
  • Euphorbia lactea ‘Cristata’ is a sport of Euphorbia lactea with a rare mutation causing a cristate fan-shaped head (7,8).
  • This plant grows slowly on its own roots, and is often found grafted onto the rootstock of Euphorbia nerifolia or Euphorbia canariensis, to give it an attractive cactiform stature (2,4,6,7,9)
 
  • Uses: The coral cactus is not a true cactus at all, but a succulent with cactiform qualities (2,5). This plants ease of care makes it a great choice for beginners as it doesn’t require much attention or frequent repotting, making it incredibly low maintenance (2,3,5,7,8). The coral cactus’s strange appearance is its greatest allure to plant enthusiasts, often being used as an accent, as its unusual crested-form makes it a unique conversation piece in any home or greenhouse (2,5).

Cultivation and Care:
  • Watering: Low
    • The coral cactus is intolerant of overwatering and will suffer quickly if it is kept in soggy soil (3,4,5,6,7).
    • However, the coral cactus is not as tolerant of prolonged drought compared to other succulents and must be watered shortly after the soil has dried out during the hottest periods of the year (4,7).
    • This plant is dormant during the winter and watering should be considerably decreased to prevent rot (2,3,7).
  • Soil: This plant needs a well-drained soil medium, and a “soak and dry” watering routine, to prevent root rot (1,2,3,4,5,6,7).
    • A sandy soil, or potting medium formulated for succulents is recommended.
    • The coral cactus should not need to be repotted often, only when pot-bound (5).
  • Lighting: Full sun
    •  The coral cactus requires full sun to thrive, however partial shade is recommended if exposed to extreme heat (1,2,3,4,5,6,7).
    • Bright light is required if this plant is grown indoors, and it should be placed in a sunny window (1,3,5,6,7).
  • Propagation: This plant grows slowly on its own roots and is often propagated by grafting a crest scion onto a Euphorbia nerifolia or Euphorbia canariensis rootstock (1,2,3,4,6,7,9).
    • This plant is difficult to propagate due to the sap, and the best time to perform grafting is during the growing season (spring/summer) (2,3,4,5,7).
    • Grafting should be done using a sharp sterile knife to create a concave V-shaped incision at the bottom of the crest, and a convex V-shaped incision in the top of the chosen rootstock (6,7).
    • A grafting wax can be applied to prevent drying until the wound heals, and a piece of twine/rubber band can be used to hold them together (6).
    • Rooting hormone is recommended for cutting propagation (4,7).
    • This plant can be propagated by seeds, however this is not commonly practiced (4,7).
  • Cold Tolerance: Tender, USDA hardiness zones 10a to 11b.
    • The coral cactus will not tolerate extreme cold and will perish if exposed to frost (1,2,3,4,7).
  • Special Accommodations: This plant rarely flowers, if ever, but will do so in the spring if inclined (1,2).
    • The seeds are hard to come by due to the rarity of flowering, and they are difficult to germinate (1,2,4,7).
    • This plant is toxic when ingested, causing nausea and vomiting, and exposure to its sap irritates the skin, mouth, nose and eyes (1,2,3,5,6,7).
    • If exposed to the skin, the sap must be washed off immediately, once it has dried it is insoluble in water and difficult to wash off, milk or a greasy lotion should then be used in this instance (7).
    • The sap should also be kept away from the eyes as it can cause blindness (7).
    • Due to its toxicity, gloves must be used while handling and it should be kept out of reach to children and pets (1,2,3,4,5,6,7). 


Sources:
1)  Euphorbia lactea 'Cristata'/RHS Gardening
2.   Euphorbia lactea ‘Cristata' | Succulents and Sunshine
3.   Euphorbia Lactea 'Cristata' (Guide With Pictures)- Succulents Network
4.   Euphorbia lactea 'Cristata' (Crested Elkhorn) - World of Succulents
5.   Coral Cactus - Eurphorbia Lactea Crest (houseplantsexpert.com)
6.   How to Care for Coral Cactus: Grafted Euphorbia lactea crest (scienceprofonline.com)
7.   Euphorbia Lactea Cristata Full Guide - Care, Fertilization, Diseases & More ... | Succulent City
8.   Euphorbia Lactea Cristata, easy care so called coral cactus (plantcircle.co)
9.   NParks | Euphorbia lactea 'Cristata Variegata'