ADVERTISEMENTS:
Let us learn about Anatomy of the Phylloclade. After reading this article you will learn about: 1. Introduction to Anatomy of the Phylloclade 2. Anatomy of the Phylloclade of Cocoloba 3. Anatomy of the Phylloclade of Ruscus.
Introduction to Anatomy of the Phylloclade:
Numerous stems are specialized for photosynthesis and take the place of leaves in the manufacture of carbohydrates. Some stems which are specialized for photosynthesis are round (e.g., Casuarina, Euphorbia tirucalli, etc.), others are flattened (e.g., Cocoloha-Muehlenbeckia platyclada), and others even have the form of leaves (e.g., Ruscus, Myrsiphyllum, Phyllocladus protractus, etc.).
Such stems as those of cacti (e.g., Opuntia, Carnegiea, etc.) are specialized both for photosynthesis and for water storage. In the following paragraphs, the anatomy of the phylloclade of cocoloba—(Muehlenbeckia platyclada—Homalocladium platycladum) and Ruscus has been discussed.
Anatomy of the Phylloclade of Cocoloba (Homalocladium – Platycladum—Muehlenbeckia Platyclada) Dicot:
ADVERTISEMENTS:
Epidermis:
The surfaces are bounded on both the sides by upper and lower epidermal layers. A thin cuticle covers the epidermis. The epidermis is interrupted by numerous stomata on both the surfaces. Distinct guard cells of the stomata and sub-stomatal chambers are visible.
Chlorenchyma:
Just beneath the epidermis there are few layers of chlorophyllous cells. The chlorophyllous cells are found only underneath the upper and lower epidermal layers. However, the chlorenchyma is not found at the edges of the phylloclade. The stomata are confined to chlorophyllous regions. There are well developed intercellular spaces among these cells. This is assimilatory tissue.
Sclerenchyma:
The multi-layered sclerenchyma tissue is found at the edges of the phylloclade. This is meant for mechanical strength. Just below the chlorenchyma there is a single layer of sclerenchyma cells, which delimits the central parenchyma and the peripheral chlorenchyma. Usually each vascular bundle is capped by a well developed sclerenchymatous patch.
Vascular bundles:
Around the central parenchyma the vascular bundles are found to be arranged in the peripheral region. The vascular bundles of the two corners are bigger in size than the remaining ones. Each vascular bundle is capped by a sclerenchymatous patch, and is composed of xylem, phloem and cambium.
The xylem consists of metaxylem and protoxylem groups. The xylem parenchyma is also present. The phloem strand lies towards periphery. The phloem is composed of sieve tubes, companion cells and phloem parenchyma. In between xylem and phloem strands there lies the cambium. The cambium is confined to the bundle.
Parenchyma:
The central region is occupied by parenchyma. It is composed of thin-walled, rounded or oval, living cells having well developed intercellular spaces. This is storage tissue.
Anatomy of the Phylloclade of Ruscus (Monocot):
Epidermis:
The phylloclade possesses two surfaces (upper and lower). Both the surfaces remain bounded by upper and lower epidermal layers. The upper epidermis consists of a single row of radially elongated epidermal cells. The epidermis is interrupted by stomata at certain places.
ADVERTISEMENTS:
The sub-stomatal chambers and guard cells with chloroplasts are distinctly seen. The upper surface becomes somewhat bulged in the central region. The lower surface in the central region becomes somewhat angular; otherwise the anatomy of the lower epidermis is quite similar to that of upper epidermis.
Chlorenchyma:
Immediately below the upper epidermis few layers of chlorophyllous cells are present. These cells are rounded or oval shaped, containing chloroplasts and having well developed intercellular spaces among them. In between upper and lower epidermis the well developed parenchyma is present.
Vascular System:
It is well developed and represented by many amphivasal (phloem surrounded by xylem) vascular bundles. The phloem bundles remain surrounded by a sclerenchymatous sheath. The phloem consists of sieve tubes and companion cells.
