Asparagales

Order of monocots

Food, Plant source foods, Flowering plats (angiospermae), Mesangiosperms, Monocots

Consumption area(s): Earth

Note: For better understanding, please read the article on flowering plants (angiospermae) first. If you come across unfamiliar words, you can click on any highlighted term to open the glossary with definitions of key botanical terms.

Introduction

Asparagales, also known as asparagoid lilies, represent one of the most diverse orders of monocot flowering plants. They are the largest monocot order, containing roughly 14 families, 1,122 genera, and nearly 36,000 species.

Description of Asparagales

While most Asparagales are herbaceous, some barely reach 15 cm in height. However, the order also includes climbing species such as certain Asparagus, as well as genera that develop into trees, which can surpass 10 meters. Nearly all members display leaves arranged in a dense rosette, either at the base of the plant or at the tip of a woody stem, though some produce leaves along the stem.

The flowers of Asparagales follow a fairly uniform scheme typical of lily-like monocots. In contrast with Liliales, their tepals are usually plain. When nectaries occur, they are located in the ovarian septa rather than at the base of the tepals or stamens.

Species with relatively large dry seeds often develop a dark outer crust rich in phytomelanin. Yet, this pigment is absent in certain groups: those with hairy seeds, species with berries, or plants with extremely reduced seeds. Although phytomelanin is frequent inside the order, it is not unique to it and is rarely found elsewhere. The inner seed coat tends to be collapsed.

Most monocots cannot thicken their stems once formed because they lack the cylindrical meristem present in other angiosperms. Asparagales, however, possess an unusual mechanism of secondary growth. This process, known as anomalous secondary growth, produces new vascular bundles around which expansion occurs.

Differences with Liliales also emerge in microsporogenesis, the stage of pollen development. This involves two meiotic divisions producing four daughter cells, but the sequence varies. In the successive type, cell walls form after each division, while in the simultaneous type, walls appear only once all four microspore are present. Liliales consistently display the successive mode, considered the primitive condition among monocots. By contrast, early Asparagales shifted to simultaneous microsporogenesis.

Classifcation of Asparagales

This order is further divided into families. Among them are:

• Amaryllidaceae (garlic, leeks, onions)
• Asparagaceae (asparagus)
• Iridaceae (saffron)
• Orchidaceae (vanilla)