| Symbol | Scientific name | Common name/Accepted name (for synonyms) | Family |
| XYDR | Xyris drummondii Malme | Drummond's yelloweyed grass | Xyridaceae
|
| XYEL3 | Xyris elata Chapman | Xyris jupicai | Xyridaceae
|
| XYEL2 | Xyris elliottii Chapman | Elliott's yelloweyed grass | Xyridaceae
|
| XYFI | Xyris fimbriata Ell. | fringed yelloweyed grass | Xyridaceae
|
| XYFL2 | Xyris flabelliformis Chapman | savannah yelloweyed grass | Xyridaceae
|
| XYFL4 | Xyris flexuosa Chapman | Xyris torta | Xyridaceae
|
| XYFL5 | Xyris flexuosa Muhl. ex Ell. | Xyris caroliniana | Xyridaceae
|
| XYIN2 | Xyris indica L. | Xyris torta | Xyridaceae
|
| XYIR | Xyris iridifolia Chapman | Xyris laxifolia var. iridifolia | Xyridaceae
|
| XYIS | Xyris isoetifolia Kral | quillwort yelloweyed grass | Xyridaceae
|
| XYJU2 | Xyris juncea Baldw. | Xyris baldwiniana | Xyridaceae
|
| XYJU | Xyris jupicai L.C. Rich. | Richard's yelloweyed grass | Xyridaceae
|
| XYLAI | Xyris laxifolia Mart. var. iridifolia (Chapman) Kral, comb. nov. ined. | irisleaf yelloweyed grass | Xyridaceae
|
| XYLA | Xyris laxifolia Mart. | laxleaf yelloweyed grass | Xyridaceae
|
| XYLO | Xyris longisepala Kral | Kral's yelloweyed grass | Xyridaceae
|
| XYLO2 | Xyris louisianica Bridges & Orzell | Louisiana yelloweyed grass | Xyridaceae
|
| XYMO | Xyris montana Ries | northern yelloweyed grass | Xyridaceae
|
| XYNE | Xyris neglecta Small | Xyris difformis var. curtissii | Xyridaceae
|
| XYPA5 | Xyris pallescens (C. Mohr) Small | Xyris caroliniana | Xyridaceae
|
| XYPA6 | Xyris papillosa Fassett | Xyris difformis var. curtissii | Xyridaceae
|
| XYPL | Xyris platylepis Chapman | tall yelloweyed grass | Xyridaceae
|
| XYSC | Xyris scabrifolia Harper | Harper's yelloweyed grass | Xyridaceae
|
| XYSE | Xyris serotina Chapman | acidswamp yelloweyed grass | Xyridaceae
|
| XYSMO | Xyris smalliana Nash var. olneyi (Wood) Gleason | Xyris smalliana | Xyridaceae
|
| XYSM | Xyris smalliana Nash | Small's yelloweyed grass | Xyridaceae
|
| XYST | Xyris stricta Chapman | pineland yelloweyed grass | Xyridaceae
|
| XYTE | Xyris tennesseensis Kral | Tennessee yelloweyed grass | Xyridaceae
|
| XYTOM | Xyris torta Sm. var. macropoda Fern. | Xyris torta | Xyridaceae
|
| XYTOO | Xyris torta Sm. var. occidentalis Malme | Xyris torta | Xyridaceae
|
| XYTO | Xyris torta Sm. | slender yelloweyed grass | Xyridaceae
|
| XYRIS | Xyris L. | yelloweyed grass | Xyridaceae
|
| YAMI | Yabea microcarpa (Hook. & Arn.) K.-Pol. | false carrot | Apiaceae
|
| YABEA | Yabea K.-Pol. | yabea | Apiaceae
|
| YELA | Yeatesia laetevirens (Buckl.) Small | Yeatesia viridiflora | Acanthaceae
|
| YEPL | Yeatesia platystegia (Torr.) Hilsenb. | Montell bractspike | Acanthaceae
|
| YEVI | Yeatesia viridiflora (Nees) Small | yellow bractspike | Acanthaceae
|
| YEATE | Yeatesia Small | bractspike | Acanthaceae
|
| YEXA | Yermo xanthocephalus Dorn | desert yellowhead | Asteraceae
|
| YERMO | Yermo Dorn | desert yellowhead | Asteraceae
|
| YOJAE | Youngia japonica (L.) DC. ssp. elstonii (Hochr.) Stebbins | Youngia japonica | Asteraceae
|
| YOJA | Youngia japonica (L.) DC. | oriental false hawksbeard | Asteraceae
|
| YOTH | Youngia thunbergiana DC. | Youngia japonica | Asteraceae
|
| YOUNG | Youngia Cass. | youngia | Asteraceae
|
| YUAL | Yucca aloifolia L. | aloe yucca | Agavaceae
|
| YUAN | Yucca angustifolia Pursh | Yucca glauca var. glauca | Agavaceae
|
| YUANA2 | Yucca angustissima Engelm. ex Trel. var. angustissima | narrowleaf yucca | Agavaceae
|
| YUANA | Yucca angustissima Engelm. ex Trel. var. avia Reveal | Yucca angustissima var. angustissima | Agavaceae
|
| YUANE | Yucca angustissima Engelm. ex Trel. var. elata Engelm. | Yucca elata var. elata | Agavaceae
|
| YUANK | Yucca angustissima Engelm. ex Trel. var. kanabensis (McKelvey) Reveal | Kanab yucca | Agavaceae
|
| YUANM | Yucca angustissima Engelm. ex Trel. var. mollis Engelm. | Yucca arkansana | Agavaceae
|
| YUANT | Yucca angustissima Engelm. ex Trel. var. toftiae (Welsh) Reveal | Toft's yucca | Agavaceae
|
| YUAN2 | Yucca angustissima Engelm. ex Trel. | narrowleaf yucca | Agavaceae
|
| YUAR | Yucca arizonica McKelvey | Yucca baccata var. brevifolia | Agavaceae
|
| YUARP | Yucca arkansana Trel. var. paniculata McKelvey | Yucca louisianensis | Agavaceae
|
| YUAR2 | Yucca arkansana Trel. | Arkansas yucca | Agavaceae
|
| YUBAB | Yucca baccata Torr. var. baccata | banana yucca | Agavaceae
|
| YUBAB2 | Yucca baccata Torr. var. brevifolia (Schott ex Torr.) L. Benson & Darrow | Spanish dagger | Agavaceae
|
| YUBAM | Yucca baccata Torr. var. macrocarpa Torr. | Yucca torreyi | Agavaceae
|
| YUBAV | Yucca baccata Torr. var. vespertina McKelvey | banana yucca | Agavaceae
|
| YUBA | Yucca baccata Torr. | banana yucca | Agavaceae
|
| YUBAB3 | Yucca baileyi Woot. & Standl. var. baileyi | Navajo yucca | Agavaceae
|
| YUBAI | Yucca baileyi Woot. & Standl. var. intermedia (McKelvey) Reveal | intermediate yucca | Agavaceae
|
| YUBAN | Yucca baileyi Woot. & Standl. var. navajoa (J.M. Webber) J.M. Webber | Navajo yucca | Agavaceae
|
| YUBA2 | Yucca baileyi Woot. & Standl. | Navajo yucca | Agavaceae
|
| YUBRB | Yucca brevifolia Engelm. var. brevifolia | Joshua tree | Agavaceae
|
| YUBRH | Yucca brevifolia Engelm. var. herbertii (J.M. Webber) Munz | Yucca brevifolia var. brevifolia | Agavaceae
|
| YUBRJ | Yucca brevifolia Engelm. var. jaegeriana McKelvey | Jaeger's Joshua tree | Agavaceae
|
| YUBR | Yucca brevifolia Engelm. | Joshua tree | Agavaceae
|
| YUBR2 | Yucca brevifolia Schott ex Torr. | Yucca baccata var. brevifolia | Agavaceae
|
| YUCA4 | Yucca californica Lemmon | Yucca whipplei var. whipplei | Agavaceae
|
| YUCA3 | Yucca californica Nutt. ex Baker | Yucca schidigera | Agavaceae
|
| YUCA | Yucca campestris McKelvey | plains yucca | Agavaceae
|
| YUCA2 | Yucca carnerosana auct. non (Trel.) McKelvey | Yucca faxoniana | Agavaceae
|
| YUCO3 | Yucca concava Haw. | Yucca filamentosa | Agavaceae
|
| YUCO2 | Yucca confinis McKelvey | Yucca baccata var. brevifolia | Agavaceae
|
| YUCO | Yucca constricta Buckl. | Buckley's yucca | Agavaceae
|
| YUCR | Yucca crassifolia Engelm. | Yucca torreyi | Agavaceae
|
| YUELE | Yucca elata (Engelm.) Engelm. var. elata | soaptree yucca | Agavaceae
|
| YUELU | Yucca elata (Engelm.) Engelm. var. utahensis (McKelvey) Reveal | Utah yucca | Agavaceae
|
| YUELV | Yucca elata (Engelm.) Engelm. var. verdiensis (McKelvey) Reveal | Verdi yucca | Agavaceae
|
| YUEL | Yucca elata (Engelm.) Engelm. | soaptree yucca | Agavaceae
|
| YUEL2 | Yucca elephantipes Regel | Yucca guatemalensis | Agavaceae
|
| YUFA | Yucca faxoniana (Trel.) Sarg. | Eve's needle | Agavaceae
|
| YUFIC | Yucca filamentosa L. var. concava (Haw.) Baker | Yucca filamentosa | Agavaceae
|
| YUFIS | Yucca filamentosa L. var. smalliana (Fern.) Ahles | Yucca filamentosa | Agavaceae
|
| YUFI | Yucca filamentosa L. | Adam's needle | Agavaceae
|
| YUFL2 | Yucca flaccida Haw. | Yucca filamentosa | Agavaceae
|
| YUFR | Yucca freemanii Shinners | Yucca louisianensis | Agavaceae
|
| YUGI2 | Yucca gilbertiana (Trel.) Rydb. | Yucca harrimaniae var. harrimaniae | Agavaceae
|
| YUGLG2 | Yucca glauca Nutt. var. glauca | soapweed yucca | Agavaceae
|
| YUGLG | Yucca glauca Nutt. var. gurneyi McKelvey | Gurney's yucca | Agavaceae
|
| YUGL | Yucca glauca Nutt. | soapweed yucca | Agavaceae
|
| YUGL2 | Yucca gloriosa L. | moundlily yucca | Agavaceae
|
| YUGR | Yucca graminifolia Wood | Yucca whipplei var. whipplei | Agavaceae
|
| YUGU | Yucca guatemalensis Baker | bluestem yucca | Agavaceae
|
| YUHAG | Yucca harrimaniae Trel. var. gilbertiana Trel. | Yucca harrimaniae var. harrimaniae | Agavaceae
|
| YUHAH | Yucca harrimaniae Trel. var. harrimaniae | Spanish bayonet | Agavaceae
|
| YUHAN | Yucca harrimaniae Trel. var. neomexicana (Woot. & Standl.) Reveal | New Mexico Spanish bayonet | Agavaceae
|
| YUHAS | Yucca harrimaniae Trel. var. sterilis Neese & Welsh | Spanish bayonet | Agavaceae
|
| YUHA | Yucca harrimaniae Trel. | Spanish bayonet | Agavaceae
|
| YUINR | Yucca intermedia McKelvey var. ramosa McKelvey | Yucca campestris | Agavaceae
|