Botany Collections
Plants are excellent indicators of climate because some species are tightly constrained to specific temperatures, humidity, and levels of shade. There have been 158 species identified in the collections at La Brea Tar Pits from wood, seeds, cones, leaves, and pollen.
To give visitors to La Brea Tar Pits a better insight into the vegetation that grew here during the end of the Ice Age, the museum has created a Pleistocene Garden. Its contents are based on the fossils recovered from Pit 91. The climate in the Los Angeles basin approximately 50,000 years ago appears to have been a coastal maritime climate similar to that currently prevailing on the Monterey peninsula, approximately 300 miles north of Los Angeles. Evidence from pollen in deep sea cores suggests that the climate was both cooler and wetter than it is today in Southern California. However, isotopic evidence from Rancho La Brea mammals and plants indicates that the rainfall was restricted to the winter. As the climate became cooler, the amount of carbon dioxide in the atmosphere decreased. Carbon dioxide is important for plant photosynthesis. Evidence from the Rancho La Brea plant material, including the 14,000 year-old fossil tree from Pit 3, indicates that late Pleistocene plants were severely stressed from carbon starvation. Low plant productivity during this period may have adversely affected food supplies for herbivores. Fossil plants recovered from La Brea are associated with at least four different vegetation communities today: coastal sage scrub, riparian (stream margin), chaparral, and mixed evergreen/redwood forest.
The following taxonomic list has been taken directly from the following reference but revisions may be necessary.
Stock, C. 1992. Rancho La Brea: A record of Pleistocene life in California. 7th ed. Revised by J.M. Harris. Science Series no.37. Los Angeles: Natural History Museum of Los Angeles County, 113 pp.
Class Bacillariophyceae (Diatoms)
Order Centrales (Centric diatoms)
Family Coscinodiscaeae
Actinocyclus ehrenbergii var. ralfsii (W. Sm.) Hust.
Coscinodiscus marginatus Ehr.
Coscinodiscus radiatus Ehr.
Melosira italica (Ehr.) Kutz.
Melosira clavigera Grun.
Stephanodiscus astraea (Ehr.) Grun.
Order Pennales (Pennate diatoms)
Family Fragilariaceae
Fragilaria bicapitata A. Mayer var. bicapitata
Fragilaria virescens Ralfs var. virescens
Fragilaria vaucheriae (Kutz.) Peters var. vaucheriae
Fragilaria construens var. binodis (Ehr.) Grun.
Meridion circulare var. constrictum (Ralfs) V.H.
Synedra fasciculata var. truncata (Grev.)
Synedra ulna (Nitz.) Ehr. var. ulna
Family Achnanthaceae
Achnanthes lanceolata (Breb.) Grun. var. lanceolata
Cocconeis placentula var. lineata (Ehr.) V.H.
Cocconeis scutellum var. stauroneiformis W. Smith
Family Naviculaceae
Anomoeoneis sphaerophora (Ehr.) Pfitz. var. sphaerophora
Caloneis bacillum (Grun.) Cl. var. bacillum
Caloneis lewisii Patr. var. lewisii
Caloneis limosa (Kutz.) Patr. comb. nov. var. limosa
Caloneis ventricosa var. minuta (Grun.) Patr. comb. nov.
Diploneis elliptica (Kutz.) Cl. var. elliptica
Diploneis didyma (Ehr.) var. didyma
Diploneis pseudovalis Hust. var. pseudovalis
Mastogloia elliptica var. danseii (Thwaites) Cl.
Navicula cuspidata (Kutz.) var. cuspidata
Navicula cuspidata var. maior Meist.
Navicula halophila (Grun.) Cl. var. halophila
Navicula mutica Kutz. var. mutica
Navicula mutica Kutz. var. cohnii (Hilse) Grun.
Navicula peregrina (Ehr.) Kutz. var. peregrina
Navicula pseudoatomus Lund
Navicula radiosa Kutz. var. radiosa
Navicula viridula Kutz. var. slesvicensis (Grun.) Cl.
Navicula pygmaea Kutz. var. pygmaea
Navicula aurora Sov. var. aurora
Navicula laneplata (Ag.) var. lanceolata
Navicula pupula Kutz. var. pupula
Neidium iridis (Ehr.) Cl. var. iridis
Pinnularia brebissonii (Kutz.) Rabh. var. brebissonii
Pinnularia borealis Ehr. var. borealis
Pinnularia viridis (Nitz.) Ehr. var. viridis
Pinnularia intermedia (Lagerst.) Cl. var. intermedia
Stauroneis anceps cf. S. a. linearis (Ehr.) Hust.
Stauroneis laterostrata Hust.
Stauroneis acuta W. Sm. var. acuta
Family Gomphonemaceae
Gomphonema affine Kutz. var. affine
Gomphonema affine var. I (Greg.) Andrews
Gomphonema angustatum (Kutz.) Rabh. var. angustatum
Gomphonema parvulum var. micropus Cl.
Gomphonema subclavatum var. commutatum (Grun.) A. Mayer
Family Cymbellaceae
Amphora ovalis var. affinis (Kutz.) V.H. ex DeT.
Amphora ovalis var. pediculus (Kutz.) V.H. ex DeT.
Amphora venata Kutz. var. venata
Amphora normanii Rabh. var. mormanii
Amphora coffeiformis (Ag.) Kutz. var. coffeiformis
Cymbella cistula (Ehr.) Kirchn. var. cistula
C. muelleri Hust. var. muelleri
C. mexicana (Ehr.) Cl. var. mexicana
Family Epithemiaceae
Denticula elegans Kutz. var. elegans
Denticula elegans var. kittoniana (Grun.) DeT.
Denticula lauta J.W. Bail. var. lauta
Epithemia emarginata Andrews var. emarginata
Epithemia turgida (Ehr.) Kutz. var. turgida
Epithemia turgida var. westermanii (Ehr.) Grun.
Epithemia adnata var. minor (Perag. & Herb) Patr. comb. nov.
Epithemia intermedia Fricke var. intermedia
Rhopalodia gibba (Ehr.) 0. Mull. var. gibba
Rhopalodia gibburula (Ehr.) 0. Mull. var. gibberula
Rhopalodia musculus (Kutz.) 0. Mull. var. musculus
Family Nitzchiaceae
Hanzschia amphioxys (Ehr.) Grun.
Nitzschia angustata var. acuta Grun.
Nitzschia denticulae Grun.
Nitzschia fonticola Grun.
Nitzschia frustulum (Kutz.) Grun.
Nitzschia hungarcia Grun.
Nitzschia ignorata Krasske var. ignorata
Nitzschia palea (Kutz.) W. Sm.
Class Charophyceae (stoneworts)
Order Charales
Family Characeae
Chara sp.
Class Pinopsida (conifers)
Order Pinales
Family Pinaceae
Pinus muricata Don (bishop pine)
Pinus radiata Don (Monterey Pine)
Pinus sabiniana Dougl. (foothill pine)
Family Taxodiaceae
Sequoia sempervirens (Lamb) Endl.
Family Cupressaceae
Cupressus forbesii Jeps. (Tecate cypress)
Cupressus goveniana Gord. (Californian cypress )
Cupressus macrocarpa Hartw. (Monterey cypress)
Juniperus cf. J. barbadensis
Juniperus californica (Carr.) Antoine (California juniper)
Monocotyledons
Order Pandanales (screw-pines)
Family Sparganiaceae
Sparganium eurycarpum Engelm. (bur-reed)
Order Najadales (naiads)
Family Najadaceae
Najas sp.
Family Alismataceae
Sagittaria sp. (arrowhead)
Family Potamogetonaceae
Potamogeton sp.
Family Zannichelliaceae
Zannichellia palustris L. (horned pondweed)
Order Poales (grasses and sedges)
Family Cyperaceae
Scirpus spp.
Eleocharis sp.
Carex sp.
Family Poaceae (grasses)
Tribe Festuceae
Bromus sp.
Festuca sp.
Tribe Sporoboleae
Sporobolus sp.
Tribe Chlorideae
Bouteloua sp.
Hilaria sp.
Order Liliales
Family Iridaceae
Sisyrinchium bellum S. Wats. (western blue-eyed grass)
Dicotyledons
Order Juglandales
Family Juglandaceae
Juglans californica S. Wats. (California black walnut)
Order Salicales
Family Salicaceae
Salix lasiolepis Benth. (arroyo willow)
Order Rosales
Family Ulmaceae
Celtis reticulata Torr. (hackberry)
Order Fagales (beeches)
Family Betulaceae
Alnus rhombifolia Nutt. (white alder)
Family Fagaceae
Quercus agrifolia Nee (coast live oak)
Quercus dumosa Nutt. (Nuttall's scrub oak)
Quercus lobata Nee (valley oak)
Order Caryophyllales
Family Polygonaceae (knotweed)
Eriogonum sp.
Rumex salicifolius Weinm. (willowdock)
Family Chenopodiaceae (goosefoot)
Chenopodium sp.
Atriplex sp.
Eurotia lanata (Pursh) Moc. (winterfat)
Family Amaranthaceae (amaranth)
Amaranthus sp.
Family Portulacaceae
Calandrinia ciliata var. menziesii (Hook.), J. F. McBride (redmaids )
Montia spathulata (Dougl.) Howell
Order Ranunculales (buttercups & crowfoot)
Family Ranunculaceae
Ranunculus aquatilis DC Water (water-crowfoot)
Ranunculus sp. (buttercup)
Family Berberidaceae
Berberis sp. (barberry)
Family Lauraceae
Umbellularia californica Nutt. (California bay)
Order Proteales
Family Platanaceae
Platanus racemosa Nutt. (Western sycamore)
Family Rosaceae
Adenostoma fasciculatum Hook. & Arn. (chamise )
Rubus vitifolius Cham. and Sch. (California blackberry)
Order Sapindales
Family Anacardiaceae
Toxicodendron diversiloba Torr. and Gray (Pacific poison oak)
Family Aceraceae
Acer negundo L. (box elder)
Family Balsaminaceae
Balsamorhiza deltoidea Nutt. (deltoid balsamroot)
Order Rhamnales
Family Rhamnaceae (buckthorns)
Rhamnus californica Esch. (California coffeeberry)
Ceanothus sp. (lilac)
Order Malvales
Family Malvaceae (mallows)
Sphaeralcea sp.
Order Apiales
Family Apiaceae (celery, carrots, parsley)
Berula erecta (Huds.) Coville
Oenanthe sarmentosa Presl.
Family Cornaceae
Cornus californica C. A. May (dogwood)
Order Ericales
Family Ericaceae (heathers)
Xylococcus bicolor Nutt.
Arctostaphylos glauca Lindl.
Arctostaphylos insularis Green
Arctostaphylos morroensis Weisl. and Schr.
Arctostaphylos pechoensis Dudley
Arctostaphylos pungens H. B. K.
Arctostaphylos tomentosa (Prsch.) Lindl.
Arctostaphylos viscida Parry
Order Polemoniales
Family Convolvulaceae
Convolvulus sp.
Family Lamiaceae (mints)
Salvia sp.
Family Scrophulariacaea
Antirrhinum nuttallianum Benth. (Nuttall's snapdragon)
Orthocarpus purpurascens Benth. (purple owl's clover)
Family Verbenaceae
Verbena spp.
Order Rubiales
Family Rubiaceae
Galium trifidum L. (three-petal bedstraw)
Family Caprifoliaceae
Sambucus mexicana Presl ex DC. (Mexican elderberry)
Order Campanulales
Family Asteraceae
Ambrosia sp.
Madia sp.
Hemizonia fasciculata (DC.) Torre and Gray
Xanthium strumarium var. glabratum (DC.) Cronquist (=X. s. calvum)
Osmadenia tenella (Nutt.) (false rosinweed)
Artemisia sp. (sagebrush)
Cirsium sp. (thistle)