THE COLOUR IN NEOREGELIAS

Believe It or Not

By: John Catlan

  1. Inner leaf colour
  2. Light blushing
  3. Temperature variation
  4. Sun tanning
  5. Ring spot
  6. Discolour syndrome
  7. Chlorophyll
  8. Variegation
  9. Finger nail
  10. Speckling
  11. Fertiliser
  12. Blood water
1. Inner leaf colour: The centre of many Neoregelias produce a flush of colour which begins with the initiation of flowering. The colour ranges from green, white and various shades of red through to purple. With some Neoregelias the colour fades rapidly while others last for twelve months or more.

2. Light blushing: The top layer of cells in the foliage of plants of the Neoregelia carolinae complex and others have the ability to flush with colour. This flush of colour is governed by light intensity, day length and nitrogen levels.

3. Temperature variation: Especially during spring with fluctuating periods of temperature, Neoregelias such as Neoregelia 'Bob & Grace' and Neoregelia 'Lambert's Pride', the green banding is initiated. Increased fertiliser may increase the banding but there is a limit. What I believe happens is the discolour-syndrome layer of cells is laid down during its growth and as the growth exceeds the normal rate it leaves gaps in the colour. All these plants are subject to sun tanning.

4. Sun tanning: Is associated with the top layer of chlorophyll cells. The same as light blushing. The difference between light blushing which will fade in decreased light is that sun tanning is fixed. Once it happens, it is there forever. The Neoregelia 'Charm', Neoregelia 'Gold Fever', Neoregelia 'Gespacho', Neoregelia 'Red Planet', etc are subject to sun tanning and hide the variation of colour in the lower layer of cells for ever, but if you turn the leaf over, you will find the spotting has not changed. In some Neoregelia concentrica hybrids you find sun tanning may affect 25cm to three-quarters of the leaf and is normally black and is fixed and is in the top layer of cells. On a dark night, shine a torch from the bottom of the leaf through the black sun tanning, you will find little green flecks, cells that did not tan. Also you can see ring spot in the lower layer of cells that the sun tanning has hidden. Sun tanning starts from the tip of the leaf and works down.

5. Ring spot: Is caused by evaporation of water from the miniscus of the cup water and droplets. The cooling effect of evaporation is so sudden that the cells on the leaf surface cannot cope and rupture. They then cease to function allowing sunlight to tan the lower layer of cells. This happens, winter or summer, shade or bright conditions. It is the variation of temperature that begins the effect. Open conditions and low humidity in winter allows for more rapid cooling.

6. Discolour syndrome: In a dense forest, the foliage can restrict the light that reaches the forest floor so that it may be as low as one percent. In these low light areas, the majority of this light is red and plants with discolour foliage have developed this adaption to absorb the maximum of red light available. The green top layer absorbs the blue light, the red light is absorbed and reflected by the bottom layer of red cells. The light that is reflected back through the green cells gives these cells a second chance to absorb the light. When you see discolour leaved Bromeliads you know they require low light.

With Neoregelia 'Charm', Neoregelia 'Gold Fever', Neoregelia 'Gespacho', Neoregelia 'Bobby Dazzler', etc all have these red cells in the middle layer of cells. I believe they are an adaption to take advantage of low light. As this does not fit the meaning of discolour, I refer to it as discolour syndrome. These plants are green spotted and look better and perform better at lower light levels. All these plants have a safety factor against high light intensity. The top layer of cells are subject to sun tanning. In the red spotted layer of cells the colour is fixed and it doesn't matter how low the light level gets within reason, the colour remains.

7. Chlorophyll: Comes in various strengths from yellow in Neoregelia 'Gold Fever' to green in Neoregelia 'Charm'. The yellow chlorophyll allows the reds to have a clear iridescent colour, while green chlorophyll darkens the red. Fertiliser will darken the chlorophyll cell and consequently darkens the red.

8. Variegation: These are stripes that run the length of the leaf and may be white, yellow, red and anything in between. The only comment is that Neoregelias that have the discolour syndrome that are variegated, the chlorophyll cells in the top layer turn white and the bottom layer stays red. Because the green disappears altogether, the red glows with a clarity that is stunning.

9. Fingernail markings: These red tips to the leaves are intriguing in that in very bright light they darken in colour and in low light they glow. Neoregelia spectabilis that has these striking fingernail markings has green centre leaves. Why? I was told it was to attract birds that would pollinate the flowers and I believed them. Then I thought about it! The fingernail colour lasts from the beginning to the end of the plant. So for four to five years, birds visit this Neoregelia spectabilis in anticipation of a four week window of opportunity to obtain nectar. Not a very cost effective pastime for birds.

10. Speckling: Neoregelia 'Barbarian' has very fine speck markings. These plants are subject to sun tanning but the centre leaves remain speckled.

11. Fertiliser: Very mild fertiliser stress will enhance colour. Too little fertiliser and any excessive stress, light, heat, cold or lack of humidity will damage plants. Too much fertiliser and green will be your favourite colour.

12. Blood water: If you tip the water out of some Bromeliads, you will find it tinged red. The explanation given is that Neoregelia growers drip their blood into the Bromeliad cups in an effort to enhance the colour. I've tracked this Bromeliad myth down to a few Tillandsia, Guzmania and Vriesea growers who are jealous of the fact our Neoregelias are colourful through their life span while their silver or green plants have to flower before becoming interesting.


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