There is just one species in the order Amborellales (Amborella trichopoda) and it is not native to the US. It is found natively in New Caledonia.

"A team of researchers presented genetic evidence (at a botanical conference in 1999) that the most primitive living flowering plant is an obscure species called Amborella trichopoda." - University of California, Santa Cruz

• FAMILY AMBORELLACEAE
  • Amborella trichopoda - May be in the collections at MOBOT - iNat

As of 2023, 6 species of Austrobaileyales have been observed in iNaturalist in the US and 50 worldwide. The most commonly observed species in iNaturalist in the US is Florida Anise (Illicium floridanum).

• FAMILY AUSTROBAILEYACEAE
  • Austrobaileya scandens - not native to US
• FAMILY SCHISANDRACEAE
  • Florida Anise (Illicium floridanum) - mostiNat observations for Austrobaileyales in the US
• FAMILY TRIMENIACEAE

The Family Chloranthaceae is the only family in this order. There is only one observation from this order in iNaturalist in the US, and it has not been verified. 36 species have been observed worldwide. They are found in Central and South America, Southeast Asia and New Zealand.

• FAMILY CHLORANTHACEAE
  • Glabrous Sarcandra Herb (Sarcandra glabra) - the most-commonly observed species worldwide in iNat and the one observation in the US (unverified).

As of 2023, 28 species of Nymphaeales have been observed in iNaturalist in the US and 76 worldwide. The most commonly observed species in iNaturalist in the US is the American White Waterlily (Nymphaea odorata).

• FAMILY CABOMBACEAE
  • Water Shield (Brasenia schreberi) - Yosemite NP - 3rd-most-common observation in iNat
• FAMILY HYDATELLACEAE
• FAMILY NYMPHAEACEAE
  • Water Lily (Nuphar sp.)
    

    Water Lily (Nuphar sp.) Rocky Mountain National Park - 1998 iNat

  • American White Waterlily (Nymphaea odorata) - mostiNat observations in US for Nymphaeales
    

    American White Waterlily (Nymphaea odorata) Gage Park, Topeka, KS - 5/19/2018 iNat

  • Giant Waterlily (Victoria) - 6 (Outside Climatron at MOBOT)
  • Spatterdock (Nuphar advena)

Ceratophyllaceae is the only family in this order. As of 2023, 2 species of Ceratophyllales have been observed in iNaturalist in the US and 5 throughout the world. The most commonly observed species in iNaturalist in the US is the Coontail (Ceratophyllum demersum).

• FAMILY CERATOPHYLLACEAE
  • Coontail (Ceratophyllum demersum) - most iNat observations in US for Ceratophyllales
  • Spineless Hornwort (Ceratophyllum echinatum)