Shoots and Spikes
Orchids are generally categorized as sympodial or monopodial. Sympodial orchids are orchids whose stem grows parallel to the ground instead of upright, and is called the rhizome. The rhizome extends and produces multiple buds along the way, which develop into branches that we know as pseudobulbs. Monopodial orchids have a single bud at the apex, or crown of the plant. If the bud of a monopodial orchid is damaged, it dies, as it cannot grow from any other part of the plant.
Think of sympodial orchids as a felled tree in the woods, parallel to the ground, but the branches are all bent upwards to the sky. In monopodial orchids, the rhizome does not branch, and grows upright like a tree, technically making it not a rhizome but an upright stem, just like an upright, normal tree.
Each orchid growth has an apical bud, in which lies the apical meristem. The apical meristem houses primordium cells[1], which are akin to human stem cells – they can become any cell that the plant needs. These primordium cells in the apical meristem are used for tissue culture – we can clone thousands of plants from one apical meristem.
As the apex grows from the rhizome in sympodial orchids, it forms a pseudobulb with leaves, which is technically a branch, and ultimately terminates in a flower. Less than ideal conditions or immaturity of the plant make the pseudobulb terminate in a leaf.
In some sympodial orchids like Dendrobium or Catasetum, the canes have buds all along where the leaves attach. This is technically the branch (in this case, the cane) branching. If you are giving your sympodial orchids the conditions that they like, the apical meristems will transform into flower primordium, which will form (if applicable) a flower stalk and ultimately flowers.
[1] https://en.wikipedia.org/wiki/Primordium
Habitats and why they are important
To understand any plant is to recognize that they are not objects. It is a selfish, human-centric thing to think that just because something neither moves nor talks means that it is an unintelligent object. Rather, it’s more accurate (and appropriate) to see plants as organisms just like we are – intelligently responding to their environments in the ways that they are able to – just moving about in a much slower timeframe. Like most plants, orchids have the gift of immortality if in the right environment. That being said, it’s essential for any grower to understand the natural environments that each orchid species comes from, and to adjust growing conditions to fit THEIR needs.
The orchid family is the MOST diverse family of flowering plants (Angiosperms) comprising about 28,000 species[1], which is about 10% of ALL PLANT LIFE ON EARTH[2] [3]). If you ask any person to name 20 plants, and if at least 2 of them are not orchids, then they don’t know plants!
Orchids are present all across the world, growing in all environments except hard tundra and hard desert. Epiphytes have only evolved in areas of either frequent year-round rains, or year-round high humidity or both. Epiphytes are plants that grow on rocks, trees, in the soil, sand, bogs, on mountains, jungles, even in a forest near you! The most northern occurring epiphytic orchid in North America is Epidendrum conopseum (syn. Epidendrum magnoliae[4]), with its range extending into North Carolina[5].
Doing a bit of research on your end about whichever species (or progenitors of whichever hybrid you have) goes a long way. Even if you know nothing about an orchid, its physiology and the way that it grows (morphology) will tell you most of what you need to know.
- Thin leaves and/or thin roots and/or a small habit[6] means that that plant needs frequent waterings.
- Thick roots and/or thick pseudobulbs and or thick leaves means that that plant needs to fully dry out between waterings/is more succulent than other orchids.
- Orchids that lack pseudobulbs (or have severely reduced pseudobulbs) like Cochleanthes and some Miltonia require to be perpetually moist and never dry out.
- Growing Monopodial orchids (Vanda, Phalaenopsis, Angraecum, etc.) means that you need to protect the crown at all costs. The crown is where all new growth for the future of the plant comes from. If that is damaged, the plant is lost.
- Growing sympodial orchids means that you will need to pay attention to the directionality of the rhizome.
The following chart summarizes this information:
Orchids have evolved each of these traits for each of their environments, but additionally, some orchids have evolved to need a particular element or pH from their environments as well. For example, many Paphiopedilum species have evolved in limestone environments[7], and some require limestone to do well[8]. Interestingly, while the soil (they are terrestrial) may have lots of calcium from the limestone, they are often growing amongst leaf litter at the forest floor, and leaves and things that rot get sour and acidic. To the layperson, this may seem counterintuitive, but in fact, the acid generated from the decaying matter frees up the calcium from fragments of limestone in the soil, and is neutralized by the calcium, thereby raising the pH and sweetening the soil, resulting in a neutral to alkaline growing condition.
Another example is Laelia milleri (syn. Cattleya milleri). This orchid grows in Minas Gerais in Brazil only along iron ore outcroppings. When iron is oxidized, it produces red, orange, and yellow rusty colors. Iron-rich soils contribute to naturally-occurring red, orange, and yellow pigments, and indeed, the flowers become more brilliant when more iron is supplemented to the growing media.
Doing research on any orchid you buy, especially looking it up in the Internet Orchid Species Photo Encyclopedia or Plants of the World Online, will go a long way towards understanding the environment that each orchid comes from. Once you understand an orchid’s natural habitat, your job as the grower is to mimic that habitat as much as possible in your growing space. That is the key to success with orchids, or any plant for that matter.
