01Platystele jungermannioides smallest orchid

The smallest orchid is not yet certain

02Grammatophyllum speciosum (giant orchid)

03 Vanilla

A. The leaves of the original orchid are arranged in a spiral, pleated fan-shaped leaves. New branches sprout from the base of the previous year's branch buds every year, and the bases of the new branches over the years together form a rhizome.

A is the basic pattern of the primitive orchid family, without pseudobulbs and terminal racemes.

The direction of morphological evolution includes several points

Uncommon type

There is obvious root cover (velamen)

exodermis

The root tip mainly appears green when exposed to light

Used to distinguish from those whose entire root is thick

Very few roots, only fleshy root ridges attached to the rhizome

Each ridge is anatomically a root, with root hairs on the outer surface and a root stem on the inner surface.

The sheath of the root structure, the core of the stem structure surrounding the terminal bud

hibernation structure

During the growing season, new branches form from the top, and lateral buds develop into new roots.

Sometimes it extends from the leaf base and is buried deep in the soil

In Orchideae (Red Door Orchid Family) and Diurideae (Double-tailed Orchid Family) this structure is multi-pillar

This structure in the orchid family is ellipsoidal

In some taxa, all roots are flat regardless of whether they are attached or not

In some taxa, in addition to the normal root system, non-absorptive roots tend to grow upward from the substrate

Possibly due to accumulation of debris from resorbed roots

But adventitious buds will also grow on the roots

Linear and slender

lignification

Soft and juicy

compound organ

Rhizome also refers to the horizontal stolons of the Goodyerinae subtribe, because in this group there is no clear boundary between the rhizome and the aerial horizontal stolons.

Single-branched orchids have no rhizomes

Morphologically, only the first branch produced from a seedling can be called a primary stem, all other stems are secondary.

Aerial stems or erect vegetative shoots are more accurate, albeit odd, terms in the case of terrestrial orchids.

In epiphytic orchids, the entire plant is aerial, and the plant branches (vegetative shoots) may be horizontal or climbing (horizontal, pendant)

It is also difficult to give the term secondary roots an alternative meaning because the term was coined by accident rather than planned.

There is no clear boundary between the two

pseudobulb

parallel veins

A

B

F

Many times the stem or pseudobulb only has one leaf

But looking at the origin of the scale leaves or leaf sheaths reveals a bi-row alternate structure.

In primitive orchids, there is spiral phyllotaxis

Shortened internodes make the plant look like more leaves are emanating from the same level

A commonly used feature in orchid morphology is the folding or rolling of leaves during development.

The original group is rolled/convolute

Duplicate patterns are more common in taxa represented by epiphytic orchids.

Curled leaves may become fan-folded or bifold as they develop

Bifold leaves evolved from fan-folded leaves in some taxa

The leaves in some fold-leaf taxa are not exactly one type or a certain standard type.

Fan folding leaves are relatively thin

However, bifold leaves that grow overlapping may be thin or extremely fleshy.

Many orchids have flat leaf tips instead of ventral and abaxial HI

No leaf sheath, insufficient support capacity of intervening meristem

In other cases, the formation of sheaths is independent of the leaves, especially when the sheaths on rhizomes and inflorescences are very small.

The leaf sheath surrounding the pseudobulb in Teuscheria is very hard and maintains the shape of the pseudobulb. The inner pseudobulb can still maintain its shape after shrinking.

The leaf base of some orchids will form a long and narrow cylindrical petiole, such as the Stanhopeinae subfamily (Stanhopeinae).

The abscission layer is lacking in many terrestrial orchids.

Most members of the Shulan and Vanda subtribes have

disappears again in highly specialized miniature orchids

In most cases, the abscission layer is between the leaf sheath and the blade.

In a few cases, such as Teuscheria and Oecoclades (no Chinese translation, African Spotted Orchid), the abscission layer is at the lower part of the petiole.

The morphology of guard cells and accessory cells is an important basis for plant classification

There are currently three modes in Orchidaceae

Accessory satellite cells exist in both Cypripedioideae and Apostasioideae, but developmental studies are unclear

racemes (panicles) of racemose branches

Inflorescence usually with only one flower

Bracts may be inconspicuous or large and colorful

Large and colorful in Cyrtopodium or Lockhartia

But the bracts and flowers are dichotomous and alternate in some taxa.

Such as Chamaeangis and Oberinia

The inflorescence in the original group is terminal and is an extension of the central axis of the branch.

In other cases, the inflorescence is lateral or basal

In view of the growth habit of monocots, the inflorescences are always lateral.

The inflorescence of Lockhartia is either cymose or determineate

In the distantly related genus Notylia, flower clusters often arise from the base of older inflorescences. If the number of this flower cluster is reduced to 1, it can be compared with the inflorescence of Lockhartia.

one exception