Exploring Cycadofilicales: Ancient Seed Ferns of the Carboniferous Era

#Cycadofilicales #Pteridosperms #SeedFerns #CarboniferousEra #AncientPlants #Botany #PlantScience #EvolutionaryBiology #Paleobotany #FossilRecord

https://en.wikipedia.org/wiki/Cycas

https://www.alpinenurseries.com.au/plant-library/zamia-furfuracea/

The general characteristics of Cycadales, also known as Cycadopsida or Cycadophyta, include:

Size Variation: While many species are shrub-sized, some can grow quite tall, reaching heights of 20–60 feet (6–18 metres).
Unbranched Central Stem: Cycads typically possess a central stem that is unbranched, characterized by thickness and a scaly texture.
Slow Growth: Most cycad species grow relatively slowly over time.
Large Terminal Rosette of Leaves: A prominent feature of cycads is the presence of a large, terminal rosette of leaves.
Compound Leaves: The leaves of most cycad species are compound, composed of numerous small leaflets.
Evergreen Nature: Cycad leaves typically remain green for extended periods, ranging from 3 to 10 years, making them evergreen.
Thick Taproot: Despite their stature, many cycad species have a thick taproot system that can extend deep into the soil, sometimes reaching depths of 30–40 feet (9–12 meters). This taproot serves the function of absorbing water from deep beneath the surface.

Diversity of Vascular Parts:

Cycads exhibit unique vascular adaptations, including the production of coralloid roots, which resemble coral formations and grow near the surface. These roots form symbiotic relationships with cyanobacteria. Through nitrogen fixation, cyanobacteria convert atmospheric nitrogen gas (N2) into ammonia (NH3), a usable nutrient for the plant. In return, the plant provides habitat and carbohydrates to the cyanobacteria. Cycads are the sole gymnosperms known to engage in such symbiosis.

The stems and seeds of most cycads are notably rich in starch. Historically, indigenous peoples, like the Seminole Indians of Florida, utilized cycad stems, such as Zamia, as a significant food source. They dried and ground the starchy stem into flour known as "coontie." Similarly, in India, the stem of Cycas circinalis is still used to produce sago flour. However, modern-day cycads hold minimal economic importance, primarily serving as ornamental plants.

Diversity of Vascular Plants

Cycadofilicales: Cycadofilicales, also known as Pteridosperms or seed ferns, were prominent during the Carboniferous period, often referred to as the "Age of Ferns." Initially mistaken for ferns due to their fern-like foliage, they were later identified as seed plants with the discovery of fossil leaves bearing seeds. Considered primitive, they thrived in the Devonian but declined by the mid-Jurassic.

Characteristic Features of Cycadofilicales:

Vegetative Organs:i. Leaves exhibited circinate vernation and were fern-like with prominent ramentum. ii. an erect plant body with monopodial branching and dichotomously veined leaves. iii. Leaves possessed a resistant cuticle, and leaf traces were relatively large. iv. The primary xylem was well-developed, usually mesarch or endarch. v. Secondary xylem and phloem were present, with tracheids bearing multiseriate border-pits. vi. Pollen-producing microsporangia resembled those of marattiaceous ferns, sometimes forming synangia.
Spore-Producing Organs: i. Ovules had differentiated integuments and vascular supply, with a developed nucellar beak. ii. Seeds were not in cones but resembled those of Cycads and were borne on modified foliage.

Examples

Alethopteris serlii (Common: Serli's Alethopteris)
Asterotheca asterophora (Common: Star-bearing Asterotheca)
Callipteridium newberryi (Common: Newberry's Callipteridium)
Corynepteris angustissima (Common: Narrow-leaved Corynepteris)
Cycas revoluta (Common: Sago Palm)
Diplothmema somervillei (Common: Somerville's Diplothmema)
Lonchopteridium polypodioides (Common: Polypody-like Lonchopteridium)
Neuropteris flexuosa (Common: Flexuous Neuropteris)
Odontopteris valida (Common: Stout Odontopteris)
Reticulopteris australis (Common: Southern Reticulopteris)
Sphenopteris obtusiloba (Common: Blunt-lobed Sphenopteris)
Zamia furfuracea (Common: Cardboard Palm)
These examples represent the diverse flora of Cycadofilicales, including both extinct and extant species like Cycas and Zamia.
These examples represent the diverse flora of Cycadofilicales, including both extinct and extant species like Cycas and Zamia.qqq