Abstract Detail

Macroevolution

Miao, Yuyan [1], Liu, Zhong-Jian [2], Wang, Meina [2], Wang, Xin [3].

Non-phylloid “megasporophylls” of cycads and their implications for seed plant evolution.

Almost all interpretations in plant morphology, evolution and systematics are hinged with a frequently unspoken core concept “megasporophyll”. “Megasporophyll” is a term used to designate the female parts of gymnosperms, and the carpels of angiosperms are also interpreted as equivalent to and derived from megasporophylls. Therefore it is not over-stating to say that the “Megasporophyll Theory” currently dominates plant systematics and morphology. However, as a scientific theory adopted by many, “Megasporophyll Theory” has never been seriously proven. On the contrary, evidence negative for this theory has been increasing, casting doubt over this theory. The assumed precursor for carpels of angiosperms according to this theory is never found in the fossil record despite long time painstaking search, making the origin and systematics of angiosperms lasting vexing mysteries. As a core concept in botany, megasporophyll implies that female parts in seed plants are foliar, and this implication is widely accepted without questioning and behind many troubles in botany. Among all seed plants the female parts of Cycas demonstrate by far the greatest similarity to the idealized “foliar megasporophyll”, and they are also the last foothold for the term “megasporophyll”. Here, using data of the earliest fossil and extant representatives of Cycas, we prove that the formerly assumed foliar megasporophyll is actually an axis. This conclusion topples the now-dominating conceptions in botany, and paves the road for new interpretation and systematics of seed plants.

Related Links:
A paper about Cycas megasporophyll

1 - Beijing Museum of Natural History, Beijing , Beijing , 100050, China
2 - National Orchid Conservation Center of China , Shenzhen , Guangdong, 518114, China
3 - Nanjing Institute Of Geology And Palaeontology, 39 Beijing Dong Road, Nanjing, N/A, 210008, China

Keywords:
Cycas
megasporophyll
Evolution
seed plant
systematics
theory.

Presentation Type: Oral Paper:Papers for Topics
Session: 3
Location: Salon 3/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 8:15 AM
Number: 3002
Abstract ID:288
Candidate for Awards:None