Parts of the Dendrobrium Query

[milan360]

Hi Orchid Enthusiasts,

I see a lot of usage of the words psuedobulbs, stem, inflorescence, bloom spike, stalk etc and it's quite tricky for an amateur to identify correctly the parts mentioned about.

3 questions:

1) Where exactly is which? Is there a thread(with drawings if possible) on where those parts are on a dendrobrium? I have actually attached my own plant (small, indoor type) for your comments.

2) Do only mature stems bloom flowers? How can we tell if a particular stem (or is it stalk?) is already at it's max ?

3) Anyone knows an indoor watering schedule for Tropical climate (Singapore) which I can follow?

Thanks in advance!

[bil]

No probs. I'd suggest that you read up of the subject by googling parts of a flower etc. That way you will gain a more extensive knowledge than can be passed on here in a couple of lines. My botanical knowledge is a tad rusty, but I'll do my best to give you a potted version, and hope that if I screw up someone will correct me.. Not all your terms correspond perfectly with orchids as their anatmy is a bit different

psuedobulbs, Those are the stalks/stems that support the flowers and leaves
spike I would use that to describe a stalk bearing flowers, but no leaves. Bloom, an individual flower.
inflorescence, flowers, If I were you all these flower terms should be individually googled and studied for how and if they relate to orchids.

I couldn't see a pic. If you are new, go make 4 random posts somewhere and then they will let you post pics.

You need to identify which den it is as there are many types with considerable differences. If we are talking about a Den Nobile, then the young cane/stem/stalk grows all summer, rests during the winter, and then in it's second year it gives flowers. It may then after the flowers, give keikis, but it most likely won't flower again.
A den phal feeds all year round, grows mostly in the spring to autumn, and flowers for most of the year. A cane can flower in it's first, second and third year sometimes.

As for a schedule, you have to again identify which denn, as den phals for example feed all yyear round, and nobiles if given fertiliser in winter will go to keikis
You need to water depending on the water retention and loss of the medium, and the type of den. Furthermore, your case may not be the same as anyone else's and will undoubtably change throughout the year,. Mine is changing repeatedly as we power down thru autumn and into winter.

[Fairorchids]

Dedrobium in the photo is Den Phalaenopsis type.

These do not require a rest period.

They should not be allowed to go bone dry. Water (drench) when just barely moist.

Give a very light dose of fertilizer every couple of weeks while plant is actively growing or blooming.

[bil]

Oooo, nice colour! I can actually see it now. Yeah, it's a den phal.

Great bloomers, if treated well will give flowers for the best part of the year.

I fertilise at every watering, but with a VERY low level as I think that is more natural.

[milan360]

Thank you senior members. Feel free to comment on the roots if needed. =)

[estación seca]

Hi milan360, Most orchid parts are not that different from other monocot plants like grass, philodendrons, palms or iris. Orchids have leaves, and roots. Many have rhizomes, which are fibrous, normally horizontal stem-like structures from which roots grow. They are not dicot plants so they don't form wood, and they don't have the kind of woody stems trees or shrubs have. If you're not familiar with what are monocots and dicots, I suggest you look it up and read about it.

Inflorescence means the entire part of any plant that bears the flowers, including any stemlike structures, small leafy things along the inflorescence called bracts, and all the flowers themselves. Colloquially, people may refer to an inflorescence as a stem, a stalk or a spike. The word spike comes from the Latin word spica, which refers to a stalk of wheat with its seeds. To a botanist, a spike is an unbranched inflorescence with one or more flowers that grow singly off the main axis. Botanists have different names for inflorescences with various degrees of branching, and the different ways flowers can be held on the inflorescence. But orchid hobbyists often call any inflorescence a bloom spike, bloom stalk or flower stem.

Orchids tend to have two different growth habits. One kind has a central growth axis, continually making new leaves from the center of the plant and continuously elongating upwards. It may branch someplace below and it may form a clump, but every growing part formed keeps growing upwards indefinitely. The inflorescence in this kind of orchid tends to come from just above a leaf, or from the very tip of the plant. Roots can come from anywhere along the stem, between leaves. If the tip of a growth flowers, it stops growing taller, but it may branch from below and keep growing. This kind of growth is called monopodial. Phalaenopsis and Vanda are monopodial orchid genera.

The other kind of growth habit produces successive growths from a base, usually from a stemlike rhizome, but sometimes from the base of the previous growth. Roots grow from the horizontal (or mostly horizontal) rhizome only, or from the very bases of the growths. Each growth pushes up in front of the one behind it, and usually has one or more leaves. Hobbyists call these growths pushing up "leads." The number of leaves on the growth, and how they are arranged, is often used to figure out what kind of orchid it is. A given growth will grow to a certain height and stop growing. An inflorescence may come from the base of the growth, from the tip, or from leaf nodes in between. This growth form is called sympodial. Dendrobium and Cattleya have this kind of growth form. Sympodial orchids tend to produce growths only from the base of previous growths, but there are a few exceptions. Many Dendrobiums and Epidendrums form new plantlets from the bases of leaves farther up the growths. These can be cut off and grown on to form new plants when large enough.

Sometimes the sympodial growth is swollen and looks like water storage tissue. In this case the formal name for this part of the growth is pseudobulb, pseudo because it isn't a true bulb like an onion or a lily. Some people shorten this to "bulb", but it is understood they aren't true bulbs. Pseudobulbs may be round, angled, tall or short. Leaves can come from the base, along the pseudobulb, or only from the tip. Many Dendrobiums, like yours, have tall narrow pseudobulbs. Some have many pairs of leaves running up the pseudobulb, and others only 1-3 at the very tip. Tall, narrow pseudobulbs in any genus are often called, colloquially, "canes" or "stems", though these are not terms botanists would use.

In your first photo, the roots are visible. The tall upright things are pseudobulbs. It is characteristic of Dendrobium hybrids with D. phalaenopsis in their heritage to have long, upright pseudobulbs. Many people refer to elongated Dendrobium pseudobulbs as canes or stems. You will never be wrong if you use the word pseudobulb.

In your second photo, the inflorescence arises from the tip of the pseudobulb, and includes the entire stemlike portion, all the little tiny leaflike things at each node along the stem, and all the flowers. Some people would also call this the spike, the flower stalk, or the flower stem. You will never be wrong if you use the word inflorescence.

Your third photo shows leaves growing from the pseudobulbs, and I think it shows the bottom portion of the inflorescence growing from the tip of the pseudobulb.

Orchids can bloom from various places along their growths. Any type of orchid will normally bloom from only one place. D. phalaenopsis hybrids tend to bloom from the tip, and maybe a few nodes below the tip in big, healthy plants. Most orchids will only bloom once per growth, but some Dendrobiums can bloom for many years from older growths. D. phal is not a rebloomer like this, but a growth that did not bloom one year, perhaps because of poor growing conditions, may bloom once, in a future year.

[milan360]

Thanks, estación seca for the very educational reply.