Miscellaneous Mesozoic Gymnosperms

Comparison of Coniferophyte Misc. Gymnosperms

	Coniferales Cheirolepidiaceae	Czekanowskiales	Pentoxylales
Leaf type	Scale-like leaves	Highly dissected megaphyll; Ginkgophyte-like Produced on very small short shoots (fascicle-like); short shoot deciduous	Simple megaphyll; resembles cycadophyte leaf; borne on short shoots like Ginkgo
Stem	Eustele; picnoxylic wood	unknown	Resembles Medullosa; polystele (5); picnoxylic wood; short shoots & long shoots
Seed-producing structure	Megastrobilus composed of ovuliferous scales & bracts; bracts larger than scales, scales lobed	Axis with bivalve capsules; each valve with row of seeds; suture has hair-like cells with pollen attached	Branched axis, each branch with teminal cone. Cone has 20 tightly packed seeds. Seeds in cupule. Seeds bilaterally symmetrical
Seeds	Small Bilateral symmetry	unknown	Small Bilateral symmetry.
Pollen-producing structure	Microstrobilus Composed of microsporophylls and 2 adaxial microsporangia	unknown	Numerous branches fused at base into shallow ring; borne at end of short shoot; branches similar to Ginkgo
pollen	Classopollis With apical pore and equatorial groove and trilete mark	unknown	Monolete.
Geographic/ geological Distribution	Triassic to Cretaceous; widespread	Laurasia (Laurussia) only; widespread in J; restricted to N. Laurasia in late J; extinct K	Jurassic only Gondwana? Known from India and New Zealand

Comparison of Cycadophyte Misc. Gymnosperms (Pteridosperms)

	Corystospermaceae	Peltaspermaceae	Caytoniaceae
Leaf type	Pinnately compound leaf with forked rachis; dichotomous venation in pinnules	Pinnately compound	Palmately compound, each leaflet Glossopteris- like
Stem	Eustele with secondary xylem interior and exterior to primary xylem; picnoxylic wood	unknown	unknown
Seed-producing structure	Dichotomizing branch with recurved cupules containing several seeds; may have been fleshy	Axis with shallow, spirally arranged cup-like structures; 10-20 seed in a ring around the periphery	Axis with fleshy cupules; several seeds inside; superficial resemblance to carpel
Pollen-producing structure	Axis with microsporophylls each with numerous microsporangia	Lateral branches with two rows of microsporangia	Pinnate sporophyl 3-4 fused sporangia at tip; anther-like
pollen	Vestigial wings	Monolete	saccate
Geographic/ geological Distribution	Triassic	Triassic	Triassic-Cretaceous

* Note: The stem information for the Corystospermaceae & Peltaspermaceae was reversed on the class handout. Please correct this in your notes.

Comparison of Cycadophyte Misc. Gymnosperms (Bennettitales)

	Williamsonia	Williamsoniella	Wielandelia	Cycadeoidea
Leaf type	Cycad like; syndetocheilic	Simple leaves; syndetocheilic	Cycad-like; syncetocheilic	Cycad-like; syndetocheilic
Stem	Cycad-like trunk; more branched than cycad	Like Willimasonia	False dichotomies; branch ends in “flower”	Fossil “beehive” 1-10 feet tall; large pith; manoxylic wood
Seed-producing structure	Perianth with ovuliferous receptacle; numerous ovules and scales Seeds in cupules	Bisexual “flower” Perianth ovulate receptacles	Bisexual “flower” not well preserved	Bisexual “flowers” with ovuliferous receptacle
Pollen-producing structure	Microsporophylls fused into cup; synangia with rows of microsporangia	Bisexual “flower” Whorl of microsporophylls	See above	Bisexual “flower” whorl of microsporophylls
pollen	monolete	Monolete	Monolete	monolete
Geographic/ geological Distribution	Jurassic Laurasia	Jurassic Laurasia	Jurassic Laurasia	Jurassic- Cretaceous Laurasia

Czekanowskiales