Identifying flower spikes in Phalaenopsis orchids

Come spring and flower spikes begin to develop in Phalaenopsis orchids. There is always some guesswork involved in differentiating between an orchid root and spike in the early stage of their development. Read on to learn how to identify a spike from a root or new shoot.

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The cooler days of winter have begun receding and warm sunny days show signs of renewed vigour in your orchids, heralding the beginning of spring. After a slowdown in winter, towards the end of winter, you will find your orchids putting out new growths. The growths may be vegetative such as new pseudobulbs, or leaves and roots. You will also notice bud spikes and sheaths filling out, making you excited with the prospect of a good bloom season for your orchids.

A drop in ambient temperature at night induces blooming in Phalaenopsis orchids

Phalenopsis orchids or the moth orchids that we generally have in our collection are complex hybrids. They have been genetically manipulated to produce beautiful blooms in abundance. These flower spikes are induced by a drop of 7-10 degrees from the ambient daytime temperature. This means that warm days and relatively cooler nights will induce blooming in these orchids.

However, blooming also depends on a host of other factors such as maturity of the plant, its genetic makeup, health, adequate fertilization and exposure to stress. Bright indirect light also plays an important role in inducing spikes in orchids.

Sympodial orchids such as Cattleya and Oncidiums bloom on mature pseudobulbs, thereby making it easy for us to recognise when they produce buds. On the other hand, monopodial orchids such as Phalaenopsis and Vanda orchids produce bud spikes on the axis of the plant. These type of orchids also produce new shoots as well as roots on the axis of the plant. Therefore, when the first nubbings appear, it’s a guessing game whether the new growth is a potential bud spike or a new root, or even a new shoot.

A spike (on left) and root  pushing out together. Notice the sheathed surface of the spike compared to the glossy plain surface of the root

While a bud spike elicits joy and excited anticipation, a root may not be welcomed with the same gusto. But I beg to differ. Roots are good news too. It actually indicates that the plant is making itself sturdy and strong at the base to withstand the weight of a long, bloom-laden flower spike. Only when your plant is fully secure will it push out a spike. So if you see the orchid pushing out roots, its’ only a matter of time before the right conditions will induce blooming in your orchid.

Spike versus root

Monopodial orchids put out new growths such as roots, shoots and spikes simultaneously. So how do you differentiate between a spike and a new growth (keiki) or a root? Well, there are a few simple ways you can predict whether the new growth is a spike or a root

  • Position of new growth
Spikes develop at the axil of the leaf, while roots emerge radially around the stem

Roots, apart from absorbing nutrients, provide the plant with proper support. To ensure this, roots develop radially from all sides of the stem, which then provide adequate support and strengthen the plant for a top heavy inflorescence.

Spikes, on the other hand, grow only from an axial bud. This is exactly the spot where the axis of the leaf begins on a monopodial orchid. Also to be noted is the fact that spikes generally appear at the axil of the third leaf from the top or crown. But they may also emerge further down if the ode has not bloomed earlier.

However, the confusion begins when roots begin emerging from the axial area of the leaf. Then you need to wait until a defined form of the new growth begins.

When the axis of the plant is inclined, the spikes do not emerge at the axil, but will emerge vertically upwards, away from the axil and towards the direction of light

Occasionally, when the plant is not growing upright, and is slanted and growing in the direction of light, the bud spikes may not emerge from the axil of the leaf, but will shift slightly away from the axil of the leaf. This is seen due to phototrophic movement of the spike. It takes the shortest vertically upward route and emerges away from the axil of the leaf in the direction of light. This can sometimes be confusing to a new grower. However, in such a case, the shape of the new growth will help confirm whether it is a bud spike, new growth or a root.

  • Direction of new growth
Spikes grow upwards towards the direction of light as opposed to roots, which grow downwards towards the medium or away from the direction of light

One way to identify a root that has developed in the axis of a leaf is to check its direction of growth. If it’s growing away from the direction of light, or is pointing towards the medium, which provides moisture, then it’s confirmed that the new growth is a root.

In contrast, a spike will emerge from the axial bud, and will begin growing upwards in the direction of light.

  • Shape and colour of the new growth
Roots are rounded and have a glossy sheen, while pikes have a darker shade of green or burnished colour

As the new growth emerges, you can easily compare with other root tips to gauge whether the growth is a root. Spikes are usually a darker shade of green than the bright green or brown coloured root tips. Root tips are also shiny, pointed, rounded and slightly translucent when compared with spikes, which point upwards, are leaf green and opaque, with a prominent flat and mitten shaped projection. This differentiation in the tissue is markedly different from that of a root, which is rounded, glossy and has a silvery sheen.

Very often, spikes may have a burnished purple/brown tinge or may be burgundy coloured based on the colour of the flowers. So this can also help in identification of flower spikes. Roots also have brown or burnished tips. But this can be verified by comparing the new growth with pre-existing root tips.

Identifying a keiki or new basal growth

Keikis or new basal shoots or new growths also develop on the axis of the plant. These growths look similar to a spike since they are sheathed, but they do differentiate into leaf shaped structures at the tip early on.

A basal keiki developing on the Phalaenopsis schilleriana

These tips will help you identify flower spikes early on. You can accordingly take special care of the orchid for a good bloom season. To learn more on how to take care of Phalaenopsis orchid spikes, you can read my post Care tips for Phalaenopsis orchid spikes.

To know more about preparing your orchids ready for blooming, you can read my post on 6 Tips to get your orchids ready for the bloom season.

Until my next, happy growing and have a great bloom season!

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