BIO 111 LAND PLANTS

STUDY QUESTIONS

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